The white lily is a symbol of the pure white elixir and stone attained at the *albedo, the white stage of resurrection which follows the blackness and death of the *nigredo. Like the white rose, the lily is a symbol of purity.
Abraham establishes the lily as the definitive alchemical emblem of the albedo—purity, resurrection, and the white philosophical mercury—locating it structurally opposite the nigredo.
, A Dictionary of Alchemical Imagery, 1998thesis