Daumal, spurred by the example of Milosz's Epistle to Sorge, produced A Fundamental Experiment, one of the most authentic and influential texts on extra-rational experience written in this century. In a bare dozen pages Daumal struggles to describe and analyze in rational terms sensations and reflections on the brink of unconsciousness and even death. His youthful experiments with tetrachloride, whose results he has corroborated from other sources, furnish his direct evidence. For nearly 20 years this evidence has left him with the absolute certainty (he repeats and underlines the word) of having entered another world. It is not, he insists, the passive, backward-looking world of dreams to which he attained but a realm of superior awareness, which he describes in visual, mathematical, and acoustic detail:

It is important to repeat that in that new state of being, I perceived and understood perfectly the ordinary state of being, the latter being contained within the former, as waking consciousness contains our unconscious dreams, and not the reverse. This last irreversible relation proves the superiority (in the scale of reality or consciousness) of the first state over the second.