The second, to divide each of the difficulties under examination into as many parts as possible, and as might be necessary for its adequate solution. - René Descartes

Divide each difficulty into as many parts as is feasible and necessary to resolve it.

But as soon as I had finished my course of study, at which time it is usual to be admitted to the ranks of the well educated, I completely changed my opinion, for I found myself bogged down in so many doubts and errors, that it seemed to me that having set out to become learned, I had derived no benefit from my studies, other than that of progressively revealing to myself how ignorant I was.

Bad books engender bad habits, but bad habits engender good books.

And even though we have read all the arguments of Plato and Aristotle, we shall never become philosophers if we are unable to make a sound judgement on matters which come up for discussion; in this case what we would seem to have learnt would not be science but history.