Summa Contra Gentiles Quotes

The study of truth requires a considerable effort - which is why few are willing to undertake it out of love of knowledge - despite the fact that God has implanted a natural appetite for such knowledge in the minds of men.

That which is asserted universally, by everyone, cannot possibly be totally false. For a false opinion is a kind of infirmity of the understanding, just as a false judgment concerning a proper sensible happens as the result of a weakness of the sense power involved. But defects, being outside the intention of nature, are accidental. And nothing accidental can be always and in all things; the judgment about savors given by every tasting cannot be false. Thus, the judgment uttered by everyone concerning truth cannot be erroneous.

God is not offended except by our acting contrary to our own good

Also pertinent to these spirits is the execution of divine works which are done outside the order of nature, for these are most sublime among the divine ministrations... And if there be anything else that is universal and primary in the carrying out of divine ministrations, it is proper to assign it to this order.

For there are some who have such a presumptuous opinion of their own ability that they deem themselves able to measure the nature of everything; I mean to say that, in their estimation, everything is true that seems to them so, and everything is false that does not. So that the human mind, therefore, might be freed from this presumption and come to a humble inquiry after truth, it was necessary that some things should be proposed to man by God that would completely surpass his intellect.

If, then, there are many gods, there must be many such perfect beings. But this is impossible. For, if none of these perfect beings lacks some perfection, and does not have any admixture of imperfection, which is demanded for an absolutely perfect being, nothing will be given in which to distinguish the perfect beings from one another. It is impossible, therefore, that there be many gods...Furthermore, given two gods that are posited as agreeing in the necessity of being, either that in which they differ is in some way required for the completion of their necessity of being, or it is not. If it is not, then it is something accidental, because that which accrues to a thing without contributing to its being is an accident. Hence, this accident has a cause, which is, consequently, either the essence of the necessary being or something else. If its essence, then, since the necessity itself of being is its essence, as is evident from what was said above, the necessity of being will be the cause of that accident. But the necessity of being is found in both gods. Therefore, both will have that accident, and thus will not be distinguished with reference to it. If, however, the cause of the accident is something else, it follows that, unless that something else existed, this accident would not exist; and unless this accident existed, the aforesaid distinction would not exist. Therefore, unless that something else existed, these two supposed necessary beings would not be two but one. Therefore, the proper being of each depends on the other, and thus neither of them is through itself a necessary being.

If, then, there are many gods, there must be many such perfect beings. But this is impossible. For, if none of these perfect beings lacks some perfection, and does not have any admixture of imperfection, which is demanded for an absolutely perfect being, nothing will be given in which to distinguish the perfect beings from one another. It is impossible, therefore, that there be many gods...Furthermore, given two gods that are posited as agreeing in the necessity of being, either that in which they differ is in some way required for the completion of their necessity of being, or it is not. If it is not, then it is something accidental, because that which accrues to a thing without contributing to its being is an accident. Hence, this accident has a cause, which is, consequently, either the essence of the necessary being or something else. If its essence, then, since the necessity itself of being is its essence, as is evident from what was said above, the necessity of being will be the cause of that accident. But the necessity of being is found in both gods. Therefore, both will have that accident, and thus will not be distinguished with reference to it. If, however, the cause of the accident is something else, it follows that, unless that something else existed, this accident would not exist; and unless this accident existed, the aforesaid distinction would not exist. Therefore, unless that something else existed, these two supposed necessary beings would not be two but one. Therefore, the proper being of each depends on the other, and thus neither of them is through itself a necessary being.

For sheer size the Summa Theologiae is rarely beaten; it is over two million words long* – and Aquinas did not finish what he had originally intended to cover. It takes the form of questions, proposed answers of competing kinds, and discussions of those answers. This is similar to the form of a university disputation in the Scholastic tradition. The size of the book meant that Aquinas’ ideas developed as he worked on it; for example, the third part of the Summa Theologiae, corresponding to the third part of the Summa Contra Gentiles on how to attain happiness, was written at the same time that he made his commentary on Aristotle’s Nicomachean Ethics, and the influence shows.

There cannot possibly be two things neither of which has a cause of its being. —Thomas Aquinas, Summa Contra Gentiles

the Summa Contra Gentiles and Summa Theologica. These last two alone total a stupefying two million words. They are a monumental fusion of learning and faith, and a reconciliation of ancient philosophy and Christian theology, without parallel even in the works of Saint Augustine. In fact, together they make Aquinas the one Christian thinker whose system can stand beside those of Aristotle and Plato—in part because it is a brilliant synthesis of the best of both thinkers.