There are times in life when the question of knowing if one can think differently than one thinks and perceive differently than one sees is absolutely necessary if one is to go on looking and reflecting at all. [Para.] People will say, perhaps, that these games with oneself need only go on behind the scenes; that they are, at best, part of those labors of preparation that efface themselves when they have had their effects. But what, then, is philosophy today—philosophical activity, I mean—if not the critical labor of thought upon itself? And if it does not consist, in place of legitimating what one already knows, in undertaking to know how, and up to what limit, it would be possible to think differently?