“The images, in other words, invite the viewer to engage in a meditation on the nature of the universe and on the links between the earthly and the divine, the corporeal and the spiritual. Of course, such a statement would be equally true of many other instances of early modern alchemical and Hermetic symbolism. I suspect that a lot of the meaning in these images and the text that accompanies them has actually been lost, due to the fact that alchemical practice depended upon face-to-face interactions (like the one between John Dee and Khunrath) which were never recorded. And this was precisely what was intended – the true secrets of early modern alchemy were intended for a small number of the “elect” and were elaborately concealed in complex and often inscrutable language when they were allowed into printed works.”
see more on his excellent blog post.