Is represented here the generaly idea of the Magnum Opus.
Chaos behind them.
Sun and Moon on the top, holding respectively :
Black Stage with a crow.
Red Stage - Rubedo as a King.
Green Stage - viridis, as a peackoc.
White Stage as Albedo represented as a swan.
Both are upon a sphere/microcosmus egg, vase of the Art, containing an Ouroboros with three head.
Assuming that these heads are for multiplicative capacity or for "Salt, Sulfur & Mercury" is not indicated clearly.