Since the internal is reflected in the external of Nature, the alchemists' modification of matter is the attempted perfecting of Nature as well as the self. As it is for the Romantic poets, Nature to the alchemists is hierophantic, being not merely "alive," but also possessing a sacred dimension extractable as the "subtle" aspect of its material reality. The redemptive process as a perfecting power thus operates in Romanticism on two levels: as the imaginative extraction of the divine dimension of the self and Nature, and through the cathartic potential of suffering, which moves passionately away from dis-ease toward a state of harmony in which individual and universal wholeness is realised.
In accord with the phylogenic law of consciousness through which unconscious projections are progressively withdrawn, Romanticism represents an evolutionary advance in that the projective aspect of alchemy is relatively absent. Instead of being outwardly projected onto matter, the alchemical archetypes are experienced in Romanticism within the imagination. Thus although the associated patterns and symbols remain similar, they are experienced with an alteration of consciousness by being more consciously related to the individual self.
Of primary significance in medieval alchemical philosophy is the imagination, which is understood as the "real and literal power to create images," as opposed to "phantasia," which merely plays with its objects.
The imagination, in contrast, is to "be guided wholly by nature," and as an "authentic feat of . . . ideation," aims not to spin "groundless fantasies," but rather to "grasp the inner facts and portray them in images true to their nature." Furthermore, the imagination is integral to the formation of the Philosophers' Stone. (erudit.org)