flood a symbol of the dissolution and putrefaction of the matter of the Stone during the black nigredo stage when water is the dominant element… ‘The waters prevailed over the earth and had dominion over it’
Abraham defines the flood as the authoritative alchemical emblem of nigredo dissolution, citing Noah’s waters directly as the scriptural analogue for the putrefactive blackening that initiates the opus.
, A Dictionary of Alchemical Imagery, 1998thesis