Analytical psychology is fundamentally a natural science, but it is subject far more than any other science to the personal bias of the observer. The psychologist must depend therefore in the highest degree upon historical and literary parallels if he wishes to exclude at least the crudest errors in judgment. Between 1918 and 1926 I had seriously studied the Gnostic writers, for they too had been confronted with the primal world of the unconscious and had dealt with its contents, with images that were obviously contaminated with the world of instinct. Just how they understood these images remains difficult to say, in view of the paucity of the accounts which, moreover, mostly stem from their opponents, the Church Fathers.

It seems to me highly unlikely that they had a psychological conception of them. But the Gnostics were too remote for me to
establish any link with them in regard to the questions that were confronting me. As far as I could see, the tradition that might have connected Gnosis with the present seemed to have been severed, and for a long time it proved impossible to find any bridge that led from Gnosticism or Neo-Platonism to the contemporary world.

But when I began to understand alchemy I realized that it represented the historical link with Gnosticism, and that a continuity therefore existed between past and present. Grounded in the natural philosophy of the Middle Ages, alchemy formed the bridge on the one hand into the past, to Gnosticism, and on the other into the future, to the modern psychology of the unconscious. ~Carl Jung; Memories, Dreams and Reflections