I am, I exist, is necessarily true each time that I pronounce it, or that I mentally concieve it. - René Descartes

Those who reason most powerfully and are the most successful at ordering their thoughts so as to make them clear and intelligible will always be best able to persuade others of what they say, even if they speak in the thickest of dialects

I am like a prisoner who happens on enjoy an imaginary freedom in his dreams and who subsequently begins to suspect that he is asleep and, afraid of being awakened, conspires silently with his agreeable illusions.

hay pocas personas que consientan en decir lo que creen, sino también porque muchas lo ignoran, pues el acto del pensamiento, por el cual uno cree una cosa, es diferente de aquel otro por el cual uno conoce que la cree,