Animadverti jam ante aliquot annos quam multa, ineunte aetate, falsa pro veris admiserim, et quam dubia sint quaecunque istis postea superextruxi, ac proinde funditus omnia semel in vita esse evertenda, atque a primis fundamentis denno inchoandum, si quid aliquando firmum et mansurum cupiam in scientiis stabilire. Some years ago now I observed the multitude of errorsthat I had accepted as true inmy earliest years, and the dubiousness of the wholesuperstructure I had since then reared on them; and the consequent need of making a clean sweep foronce in my life, and beginning againfrom the very foundations, if Iwould establish somesecure and lasting result in science.

-Descartes, Rene¤
Meditationes,1st meditation (translated by G E M Anscombe and Peter Geach).