In the late nineteen century Sigmund Freud became convinced that some symptoms were determined by unconscious motives, and he set out to demonstrate this fact. How “obvious” this may appear to us today only shows how easily cutting-edge ideas may become blunt and fall into stuporous common sense as soon as they enter what is curiously called “public knowledge”. Very curious indeed, as public knowledge appears to equate to a knowledge that we have lost sight of, whereas for Freud—and for those who continue to keep his endeavour alive—it is precisely the reverse that had always been at stake: to articulate the principles of a knowledge so private that “unreasonable”, “irrational”, “devilish” even, have been words used to qualify it.