Man and Sin by Piet Schoonenberg (1964) 2.3 UZ

[For example, moderns could not believe in or comprehend the medieval practices of alchemy, a pre-modern inquiry that confounded all three categories of existence.

Perhaps, the first modern to realize that ‘alchemy was not ridiculous’ was Carl Jung. However, he could not quite figure out the categories of existence indicated by these fusions of mystical hints, recipes and images.]