The following is a summary from the book The Doctrine of Vibration, An Analysis of the doctrines and Practices of Kashmir Shaivism, by Mark S.G. Dyczkowski (State University of New York Press, isbn 0-88706-431-0. I find this book a very good explanation of Tantra. Basically I don't attach any importance to the fact that it comes from Kashmir, although I will point out (as in the book) some differences with Vedanta teachings.
In other articles I have given you an idea of the Tibetan Buddhism concepts about who we are and what life is about (Who am I?), and a schematic overview of the same in Tantra (Tantra Cosmology). Why give another article about the same subject? Well, this article, the Doctrine of Vibration, gives you a more comprehensible view about it all. Instead of many names and schematics (as in Tantra Cosmology), you will get more understanding and a more encompassing view of what life is about. Instead of seeing life as a gradual path to enlightenment (as in Who am I?), you will see that the whole universe is pulsation between two apparently different realities, a vibration in which we all partake.
Always be aware, that no matter what is explained here, it is all within you, it is you, it is all about you. For many readers, this is not easy reading. In essence it is about a simple concept: the Absolute and its manifestation. It is the understanding of this concept that is difficult for most people, because they grew up in a materialistic world with no education in this matter. Summarizing this book was not easy, so this article might not be that fluid. It serves as an introduction, if you feel you want to know more, I recommend reading the book. It is one of the best books I have read.

The Doctrine of Vibration 

1. Integral Monism of Kaishmiri Shaivism

An impressive title for the first chapter, but before we explain monism, we need to understand the underlying dualism of creation.
A basic concept in Samkhya is the duality of Purusha and Prakrite. Purusha is the person, the Self; Prakrite is Nature, the outer physical world, including the body and the mind. Purusha is pure sentient consciousness; Prakrite is thoughts, perceptions and the like. Purusha, we could also say the inner divine nature, and does not act or change. It is and will always remain the same, unmoved. Prakrite is change and activity. Samkya looks at these two concepts in the following way. When man identifies himself with Prakrite, Nature (what most of mankind does), Purusha, the Person is "bound" by Prakrite, Nature. When one discriminates between the two, then awareness is brought back to the person; then the Person is "freed". This is what others call enlightenment.
In Advaita Vedanta, the Self of an individual is seen as beyond the specifications of Nature. Although each person has a Self, one Self is seen as not being different from another Self. Advaita Vedanta says that there is only one Self, and that is called Brahman, the Absolute. Brahman is the unconditioned ground, the essential nature of the world of appearances. Everything exists because the Absolute is their essence, their being. This means that there are no independent realities, that is, independent from Brahman. All things exists because the Absolute is their being. When we talk about Brahman and Maya (like the Person and Nature), we say that Maya does not exist as separate from Brahman. Maya is another form of Brahman, and part of Brahman. The problem with Vedanta is that they see duality as a provisional reality, or illusionary, and that one has to reject it in order to identify with the only Reality, Brahman.
Kaishmiri Shaivism sees it differently. One does not have to reject duality, it is not illusionary. Both Brahman and Maya, unity and duality are one, are coexisting. They are both expressions of the Absolute. Maya, the world, Nature, represents a level of manifestation within the Absolute which in the process of emanation appears as the duality or multiplicity of manifestation.
In Advaita Vedanta, one denies desire because it individualizes attention, dispersing it among the objects of desire, which are seen as unreal as opposed to the Absolute which is real. Thus one withdraws from the finite to return to the infinite.
In Kaishmiri Shaivism one withdraws from the finite to the infinite, but one also goes on an outward journey from the infinite to the finite, because both the finite and the infinite have an intimate connection. The finite is not seen as unreal, but as a symbol of the infinite. There is no real distinction between them. Those two movements constitutes Spanda, a key concept in Kaishmiri Shaivism. Spanda is the pulsation of the Absolute in different phases of being. There are no opposites like subject and object, unity or duality, absolute or relative. They are just different phases of the universal vibration of the Absolute. The goal is to realize or be at once infinite and finite. One does not turn away from appearances (like in Advaita Vedanta), but one realizes that the Absolute manifests all things. Spanda, the eternal pulsation of the Absolute, oscillates between a passion to create and dispassion from the created. Through it the Absolute transform itself into all things and then returns back into the emptiness of its undifferentiated nature.
In Kaishmiri Shaivism the Absolute is seen as pure consciousness (=being). The Absolute is an eternal all-pervasive principle, the highest reality, the nature of all entities eternally and blissfully at rest within its own nature. the Absolute is the nature of the Self (and thus of us all). The Absolute is divine, it is Shiva, the Lord of the Universe. It is full of conscious activity through which it generates the universe, and reabsorbs it into itself at the end of each cycle of creation.
Thus we speak of monism, as everything resides within this one absolute consciousness. It sustains all things, it embraces all things, it pervades all things. All things are appearances within the absolute consciousness, but nevertheless real (in contrast to Advaita Vedanta where appearances are seen as unreal or illusionary). All things appear external (out there, outside ourselves), but they do not have a being on their own. They do not exist as separate entities on their own. Everything is contained within consciousness. What we see as objects are manifestations of consciousness. The events which constitutes the universe are always internal events happening within consciousness because their essential nature is consciousness itself. If a physical object were totally material, and independent or external to consciousness, it could never be experienced. The universe and consciousness are two aspects of a whole. The universe is an attribute of consciousness which bears consciousness as its substance.
Consciousness creates its own forms. But because the perceived and the perception are identical, there is no perceived object at all. The so-called outer world is merely a flux of cognitions. Nevertheless the world is a real creation of consciousness, as 'congealed' or 'contracted' forms of consciousness. Therefore everything bears a trace of consciousness, even stones.
Individual consciousness is identical with absolute consciousness. There is nothing else. Although absolute consciousness always remains one, it can perceive distinctions between one entity and another, without this engendering any distinction within it. Thus we say that different entities have the same undivided essence or nature.
In Maya, every entity, in its specific manifest form, is defined as that which distinguishes it from all else and from which it never differentiates. But at the level of pure consciousness, everything is realized to be part of the fullness of the experiencer and hence no longer bound by the conditions which impinge on the object. Here one experiences every particular individual as the sum total of everything else.
 

2. Light and Awareness

Absolute Consciousness has two aspects:
Prakasha = The Light of Consciousness
Vimarsha = the creative reflective or self-awareness of its own being
Lets first talk about Prakasha. Prakasha is the Light of Consciousness, the pure luminosity, the unchanging ground and essence of everything that appears. everything appears as their own specific nature, but it is made apparent by the Light of Consciousness, and it has the Light of Consciousness as their source.
The universe is nothing but the shining of the Light of Consciousness within itself. This is an important statement, as nothing exists outside of it. Consciousness becomes manifest in the radiant vibration of this Light. Although shining as all things, and creating diversity, there is no division within itself. A created object just has a form it assumes, and is not a separate entity.
This Light of Consciousness is also called Shiva, who creates and freely imposes on himself countless limiting conditions through which he becomes manifest in limited forms. At the same time he abides unchanged as the supreme experiencer. This freedom is an important aspect of him. He is free to be both single and diverse, both formless and omniform at the same time, in contrast with the doctrine of Samkhya where Consciousness is seen as always being formless and separate from created forms.
So this Light of Consciousness is the Eternal Now, the Present, what one calls God, or Shiva, or Bhairava. It illumines itself. It reflects on its own nature, thus creating the universe. Consciousness illumines itself in the course of making the universe manifest. While this is happening Consciousness remains the unchanging witness of all the events in the universe.
In relations to perception or cognition, Consciousness has three aspects:
the illuminator
the illumined universe
the Light of Knowledge (Prakasha) which illumines it.
We could see this a subject, object and the means of knowledge which makes cognitive awareness possible. These three aspects are always together.
Symbolically, we can compare the Light of Consciousness with an infinite, perfectly polished mirror (this symbol is also known in Dzogchen), within which the entire universe is reflected. As the mirror does not change by the reflected images, so the Light of Consciousness is free to be both immanent and transcendent without compromising its unity or denying the reality of the manifest universe. Consciousness is like the mirror which reflects objects within itself. it has the power to manifest entities that are like reflected images, which appear separate from one another, without compromising the oneness of consciousness.
So, the entire universe is like a reflection, but there is no object outside the mirror of consciousness which would provide the reflections. It is Consciousness itself that creates all the reflections spontaneously.
The second aspect of Absolute Consciousness is Vimarsha, self-awareness, or the act of reflective awareness. In an entity, thought-constructs obscure the light of the subjects' immediate perception. Thus its awareness shifts from pure consciousness to objective consciousness. Thus we experience the objective world. it is an awareness of the images that appear within the mirror of Light.
Consciousness must reflect back on itself to know itself and what appears within it. Vimarsha, or self-awareness, is the power of consciousness by virtue of which it can understand or perceive itself, and examine the events that occur within it. Through this awareness, the Light knows itself to be the sole reality and so rests in itself. It enjoys perfect freedom and it is satisfied in the knowledge that it is all that exists, be it subject, object or means of knowledge.
We often talk here in terms of universal consciousness, but the same holds true for individual I-consciousness (Aham), which is formed by the powers of the Absolute. By contemplating its own nature, consciousness assumes the form of all the planes of existence from the subtlest to the most gross. The power of reflection is thus the inherent creative freedom of the Light of Consciousness to either turn in on itself introspectively and be free of its outer forms, or move out of itself to view its outer manifestations. In harmony with the oscillation (Spanda) of awareness between these two polarities, the universe of manifestation is incessantly renewed and is the essence of the vitality of its pulsation.
Individual and universal consciousness are not two separate things, they are one. The same process operates in both. The only difference between them is that in the case of individual consciousness, these processes are restricted or limited representations of the maximally expanded operation of universal consciousness.
 

3. Spanda: The Universal Activity of Absolute Consciousness

When Absolute Consciousness self-reflects, it creates a motion, a transition from uncreated state of Being to the created state of Becoming. When the inner Being shines, it manifests as outer becoming. They are the two faces of universal consciousness. The outer face of Becoming is the diversity and continuous change of the universe: the object, that is, the apparent material universe we perceive. There is no separate material universe out there, there is only a change in consciousness. Internality is the state of oneness with the subject, while externality is the state of separation from it.
Although we are saying that Absolute Consciousness creates motion, a movement from Being to Becoming, this is essentially an act of perception because the pure Being is inaccessible to conceptual representation. Knowing this, we can say that creative action or movement can be seen as a sequence in space and time. Within the Absolute there is non-successive action. Reality in the Absolute is experienced as a single, unchanged whole. In the Absolute there is not time. In the universe or movement of awareness from one perception to the next is the basis of our sense of time passing.
We perceive action of something that follows something else. But there is no thing that comes out of another thing, because this implies that they are two different, separate entities. In reality there is only consciousness that transforms from one consciousness into another. This marks the creation of a new experience and the destruction of the old.
This ever changing consciousness that constitutes the universe is seen in Vedanta as being unreal and the domain of illusion, or Maya. In Kashmiri Shavaism, the manifestation of the universe, being the emanation of the unchanged Absolute Consciousness which remains one with its emanation, is a real event, and not just an apparent change in the essentially undivided nature of the Absolute.
Spanda, the vibration of consciousness (=the universe) has three aspects by which all things come into being: will, knowledge and action.
A being has an incessant flow of consciousness through its will to Be. The outpouring of this will to exist expresses itself both as the active cause of individual beings and the passive assent to Being that is expressed through the individuality of all that partakes Being. The will is a form of consciousness associated with a specific goal which it reflects on as its objective. It will remain fixed on its goal. For the yogi it is important to to reflect upon his own nature and to gain direct insight that his will (and perception and action) are not independent from the universal pulsation of his own authentic nature.
A being desires to know the expansion of consciousness as its goes through its transformation. Knowledge, the second aspect of Spanda, links perception together and accounts for their individual emergence within the field of awareness.
The third aspect of Spanda, is action. It is an act of awareness, free in every way. This freedom of action of Being cannot be grasped when our consciousness is in the sphere of objectivity (the material plane). When in the sphere of objectivity, the ignorant sees himself bound by the law of action and reaction (karma). Therefore we should ever be conscious of Spanda, the recurrent activity of consciousness, Thus we can catch a glimpse of our authentic identity and realize our inherent freedom.
 

4. Shiva and Shakti

Shiva and Shakti are two concepts from the Hindu tradition (read my article of Tantra Cosmology). They are seen as God and his omnipotent power, his creation. In our finite vision we see them apart, in our infinite vision we realize their unity. In Kashmiri Shavaism this primordial couple is Shankara and His Spanda energy. Spanda is the immanent, actively emergent aspect, while Shankara, although one with Spanda, is the pure, unchanged experiencer. These opposites separate and merge in rhythm. When they separate, the universe is experienced as a reality set apart from consciousness. When they unite they are experienced as a unity.
The reflective self-awareness of Shankara begins to generate thought forms within itself. Thus consciousness devolves and becomes the thinking mind. Then Shankara assumes the form of a human personality residing in a world of limitations and diversity. Hs consciousness becomes extroverted and generates out of itself a subtle body with which it transmigrates from one physical organism to the next. The awakened yogi identifies himself with Shankara. The unenlightened wrongly identifies himself with the body. His ego is just a thought construct and hence limited and artificial.
 

5. Shakti Chakra: The Wheel of Energies

Consciousness spontaneously and continuously forms ever new patterns of energy on its surface. These patterns are like waves on the sea. We observe these forms as entities and objects that come and go, rise and fall in consciousness. The arising and subsiding of each wave of cosmic manifestation is marked by a regular sequence of events. Following one after another in recurrent cycles, each sequence is symbolized by a rotating wheel. These Wheels collectively represent the primal form of all experience. As each wheel rotates, one power after another becomes active, taking over from the one that went before and blending into the one that follows. Together, all those Wheels of Energy are the vibrant radiance of the Light of Consciousness.
Although the Wheels of Energies are innumerable, only a few are important. The most important is the Wheel of the Absolute, also called the Goddess of Consciousness, from which all other Wheels emerge from and eventually dissolve in it. It is a twelve spoked wheel (it has twelve powers), representing the cognitive cycle. The yogi pays attention to the movement of this Wheel, as it moves from the center of pure consciousness to the periphery where it becomes manifest as sense objects. In this way the yogi comes to realize that all is contained within, and generated through, the cycle of consciousness. The yogi needs to identify with the Lord of the Wheel who resides in the center of this Wheel as the pure I-Consciousness behind the emanation and movement of its power. In its center he is free, fully awakened, liberated.
 

6. The Divine Body and the Sacred Circle of the Senses

To know as common man knows is the very essence of bondage; freedom is to know reality as God knows it. The yogi must recognize his own authentic Being by being as God is. This is achieved by a pure and intense act of self-awareness in which the old mode of understanding reality is dropped in favor of a new and deeper knowledge of oneself as unlimited, infinite consciousness. Bondage is a false identification with the physical body and liberation a true identification with the cosmic body. This process is also applied to the senses of the body.
At the lower level of consciousness, the physical senses are hardly more than instruments of perception. At the higher level the senses are recognized to be spiritual forces operating within sacred consciousness. Kashmiri Shaivism teaches that the senses can serve as a means to self-realization. The yogi can take pleasure in sense objects, if he maintains an awakened, mindful attitude and does not blindly follow his natural inclinations as does an animal with a bare minimum of self-awareness. All pleasure is essential spiritual. It is a state that the subject experiences and not a property of the object. It is a small wave or pulse in the universal vibration of consciousness. The yogi must fix his attention on the source of pleasure, freeing his mind of all disturbing thoughts and so make the transition to a state of awareness in which his personal concerns are transcended in the pervasive experience of consciousness. He does not crave for the pleasure of the senses, but makes use of them to project him beyond the realms of physical, transitory objectivity into the eternal sphere of consciousness.
 

7. The Path to Liberation

One needs to understand that reality is the essential nature of all things. Although it is universal and everywhere the same, it is understood as the essential and specific nature of each existent as its "own nature". In the case of the individual soul it is even more specific, more personal as his own "own nature". Belonging to none other than oneself, it is the pure subjectivity who perceives, experiences, enjoys, reflects, thinks and senses as well as being the conscious agent who creates every possible form of experience in all the states of consciousness. Thus, one needs to regain possession of oneself. One must lay hold of oneself and abide in his own authentic nature. Reality coincides with one's own most fundamental state of being, free of all contrasts and contradictions. One must penetrate through the pulsing fluctuations of objectively experienced states and perceptions at the surface level of consciousness and gain insight into the timeless rhythm of one's own nature manifest in the universal arising and falling away of all things.
The spiritual ignorance consists essentially of our contracted state of consciousness. Therefore we need to expand it to reveal our authentic nature as this expanded state itself, which is the universal vibration of consciousness. Along the way to this supreme realization consciousness develops, as veil after veil is lifted, until it becomes full and perfect in the absolute which encompasses within itself all possible formats of experience.
For the yogi there are three means to Realization. In the Divine Means the yogi is carried to the supreme level of consciousness by a powerful and direct awareness of reality. In the Empowered Means, the practices function within the mental sphere by reconverting thought back into the pure consciousness which is its source and essence. In the Individual Means the practices operate in the individual soul's sphere of consciousness. Any spiritual discipline which involves the recitation of mantras, postures of the body, meditation on a particular divine or cosmic form and concentration on a fixed point, belongs to this category.
There is also the method of No-Means, to which the other three methods ultimately lead. No-Means is the direct experience of reality as uninterrupted awareness, when the yogi has penetrated into his true awareness. Those who are in the realm of No-Means recognize that the light of consciousness shines as all things. No-Means is the experience of the absolute beyond transcendence and immanence, beyond Shiva and Shakti.