The First matter in alchemy is thought of as the fusion of spirit and matter, manifestation of the godhead.
It is also known as prima materia, and it was formless and constituted the darkness from which the universe was subsequently formed.
The alchemist Thomas Vaughan described it in his Anthroposphia Theomagica:
“I conceive it (to be) the effect f divine imagination, acting beyond itself in contemplation of that which was to come, and producing this passive darkness”.
Vaughan further described that the “splendour of the Word” cast the darkness down into the abyss of the formless night and eventually the divine spirit produced light and life from that darkness. A.G.H
Drury, Nevil. The Watkins Dictionary of Magic. London. Watkins Publishing. 2005. p. 103