Commentary on the First Book of Euclid's Elements

how is it not necessary to say that those demonstrations which are constituted from sensible things are superior to those derived from things that are always more universal and simple? For we say that the causes are everywhere appropriate to the demonstrations for the sake of hunting down the object of inquiry. If, therefore, the particular is the cause of the universal, and the sensible the cause of the dianoetic rationally grasped, what mechanism forces one to refer the definition of demonstration to the universal rather than to the divisible, and to declare the essence of dianoetic things to be more akin to demonstrations than to sensible things? For even if someone were to demonstrate that the isosceles has angles equal to two right angles, and that he knows the equilateral and the scalene in this manner, he who has demonstrated this for every triangle simply and by itself possesses the science. And again, the universal is better than the particular for the sake of demonstration; and following this, demonstrations are derived more from universals, and the things from which demonstrations arise are prior and naturally antecedent to particulars and are the causes of the things demonstrated. Therefore, the demonstrative sciences are far from looking to the posterior and dimmer things of sense-perception, and instead look to those things grasped by dianoia and which are more perfect than those known by sense and opinion.

Furthermore, we say a third thing: that those who assert these things also make the soul more dishonorable than matter. For if matter receives the essential, more real, and clearer things from nature, while the soul