Another friend of mine, [perhaps Frederick Eckstein, who was a Buddhist monk for a time] whose insatiable craving for knowledge has led him to make the most unusual experiments and has ended by giving him encyclopaedic knowledge, has assured me that through the practices of Yoga, by withdrawing from the world, by fixing the attention on bodily functions and by peculiar methods of breathing, one can in fact evoke new sensations and coenaesthesias in oneself, which he regards as regressions to primordial states of mind which have long ago been overlaid. He sees in them a physiological basis, as it were, of much of the wisdom of mysticism. It would not be hard to find connections here with a number of obscure modifications of mental life, such as trances and ecstasies (21, 67)