back to Blackness or Nigredo
The circle is both an enclosed vessel as a symbol for perfection, the goal of the Great Work.
The first stage of the Great Work is characterized by putrefaction or decomposition of the Matter, here symbolized by the body.
The black crow is a well known symbol for this phase.
The two cherubim symbolize the process of volatilization, that is becoming aware of your inner world, which is more subtle than our physical world.
Fire and Wind is the energy and effort one has to invest in the process, and one needs to keep that fire going.
The Moon and Sun are the two phases to come: Whiteness and Redness. Together with the stars, inscribed with planetary symbols, they form the seven planets or metals, which are seven different, more detailed stages in the Great Work