Hypochondriac patients defy medical practice, misuse medical language and discourage medical classifications. Their peculiar use of medical knowledge impoverishes the relational dimension, obscures the personal history as if the patient wanted to hold, to control and to maintain some obscure object within his body. When this hypochondriac defence is not powerful enough, the psychiatric condition becomes much worse. There must be some serious necessity to substitute to the obscure object of desire, the object of a universal knowledge; this necessity may happen in selective conditions. The psychodynamic study of such cases leads to the following hypothesis: decompensation occurs when the patient is no longer able to maintain simultaneously two antinomic positions toward the other: to keep his place and to keep the object of his desire. Consequently, he tends to materialize this object, in which he believes, wanting simultaneously to keep it inside and to reject it outside. Of course, this fundamental misunderstanding about desire leads the patient to ask impossible questions to medicine: naming the object (no longer of desire but indeed of faith) and expelling it (so asks he, but he does not really want). This constitutes, of course, a religious use of medicine: it is impossible for our knowledge to have a universal meaning and to respond exhaustively about each peculiar history.