Summary. — The ethico-social problems examined in this article concern psychopharacology, which is to say such pharmacological products as act upon the brain and thereby directly condition human behaviour. An at­tempt is made in this article to determine specifically the significance and the value of so-called «hallucinogenic» drugs in relation to religious experience in general, and to mystical phenomena in particular. There clearly — and worryingly — emerge from this inyestigation the illusory nature of any intended « artificial paradise » and the extremely negative consequences of the use of such drugs