Nothing can be imagined which is too strange or incredible to have been said by some philosopher. - René Descartes

But this could not be the case with-the idea of a nature more perfect than myself; for to receive it from nothing was a thing manifestly impossible; and, because it is not less repugnant that the more perfect should be an effect of, and dependence on the less perfect, than that something should proceed from nothing, it was equally impossible that I could hold it from myself:

In order to determine whether we can know anything with certainty, we first have to doubt everything we know

ART. 17. The functions of the soul Having thus considered all the functions that pertain to the body alone, it is easy to recognize that there remains nothing in us that we should ascribe to the soul except our thoughts, of which there are two main kinds: the actions of the soul and its passions. By its actions I mean all our volitions, since we experience these as coming directly from our soul, and as apparently depending on it alone. Whereas, on the other hand, the term ‘passions’ can be applied in general to all the kinds of perception or knowledge to be found within us, because it is often not our soul that makes them what they are, and because they are always produced in us by the things they represent.