For I found myself embarrassed with so many doubts and errors that it seemed to me that the effort to instruct myself had no effect other than the in… - René Descartes

Some years ago I was struck by the large number of falsehoods that I had accepted as true in my childhood, and by the highly doubtful nature of the whole edifice that I had subsequently based on them. I realized that it was necessary, once in the course of my life, to demolish everything completely and start again right from the foundations if I wanted to establish anything at all in the sciences that was stable and likely to last.

i manifestly understand that there is more reality in infinite than in finite substance, and that therefore the perception of the infinite in me must be in some way prior to that of the finite: the perception of god, in other words, prior to that of myself. for how could i possibly understand that i doubt, and that i desire, that is, that there is something lacking in me, and that i am not completely perfect, if there were no idea in me of a more perfect being, by comparison with which i could recognize my own shortcomings?

En realidad, la hipótesis del genio maligno ni es un juego ni un círculo de hierro, sino un movimiento dialéctico, muy importante en el curso del pensamiento cartesiano. Repárese en que la hipótesis del genio maligno, necesita, para ser destruida, la demostración de la existencia de Dios. Sólo cuando sabemos que Dios existe y que Dios es incapaz de engañarnos, sólo entonces queda deshecha la última