The science [geometry] is pursued for the sake of the knowledge of what eternally exists, and not of what comes for a moment into existence, and then perishes.
Wisdom always makes men fortunate: for by wisdom no man could ever err, and therefore he must act rightly and succeed, or his wisdom would be wisdom no longer.
We must infer that all things are produced more plentifully and easily and of a better quality when one man does one thing which is natural to him and does it at the right time, and leaves other things.
Those who have a natural talent for calculation are generally quick-witted at every other kind of knowledge; and even the dull, if they have had an arithmetical training, although they may derive no other advantage from it, always become much quicker than they would have been.