Foucault (quoted by Duden): "There are times in life when the question of knowing if one can think differently than one thinks, and perceive differently than one does, is absolutely necessary if one is to go on looking and reflecting at all [...] But then, what is philosophy today--philosophical activity [...] if not [the] endeavor to know how and to what extent it might be possible to think differently?" (from The Use of Pleasure, vol. 2 of The History of Sexuality)