The fact that Brother Klaus, on his own admission and according to the reports of reliable witnesses, lived without material sustenance for twenty years is something that cannot be brushed aside however uncomfortable it may be.
In the case of Therese of Konnersreuth there are also reports whose reliability of course I can neither confirm nor contest, that for a long period of time she lived simply and solely on holy wafers. Such things naturally cannot be understood with our present knowledge of physiology. One would be well advised, however, not to dismiss them as utterly impossible on that account. There are very many things that earlier were held to be impossible which nevertheless we know and can prove to be possible today.
Naturally I have no explanation to offer concerning such phenomena as the fast of Brother Klaus, but I am inclined to think it should be sought in the realm of parapsychology. I myself was present at the investigation of a medium who manifested physical phenomena.
An electrical engineer measured the degree of ionization of the atmosphere in the immediate vicinity of the medium. The figures were everywhere normal except at one point on the right side of the thorax, where the ionization was about sixty times the normal. At his point, when the (para-psychological) phenomena were in progress, there was an emission of ectoplasm capable of acting at a distance.
If such things can occur, then it is also conceivable that persons in the vicinity of the medium might act as a source of ions-in other words, nourishment might be effected for the passage of living molecules of albumen from one body to another.
In this connection it should be mentioned that in para-psychological experiments decreases of weight up to several kilograms have been observed during the (physical) phenomena, in the case both of the medium and of some of the participants, who were all sitting on scales. This seems to me to offer a possible approach to an explanation. Unfortunately these things have been far to little investigated at present. This is a task for the future. ~Carl Jung; The Symbolic Life, The Miraculous Fast of Brother Klaus; Pages 660-661.