Mysterium Coniunctionis was first published in the Collected Works of C.G. Jung in 1963. For this second edition of the work, numerous corrections and revisions have been made in cross-references to other volumes of the Collected Works now available and likewise in the Bibliography.

Mysterium Coniunctionis was Jung's last work of book length and gives a final account of his lengthy researches in alchemy. It was Jung's empirical discovery that certain key problems of modern man were prefigures in what t he alchemists called their 'art' or 'process'. Jung maintained that 'the world of alchemical symbols does not belong to the rubbish heap of the past, but stands in a very real and living relationship to our most recent discoveries concerning the psychology of the unconscious'. The volume includes ten plates, a Bibliography, an Index, and an Appendix of original Latin and Greek texts quoted in the work.