"Whatever is made by God must be made from something or from nothing. If it is made from nothing, it is created. If it is created, it begins to be. But if it is made from something, it is generated. The question is whether it is possible for a thing to be created and yet not have a beginning in time."
Now the end which befits a multitude of free men is different from that which befits a multitude of slaves, for the free man is one who exists for his own sake, while the slave, as such, exists for the sake of another. If, therefore, a multitude of free men is ordered by the ruler towards the common good of the multitude, that rulership will be right and just, as is suitable to free men. If, on the other hand, a rulership aims, not at the common good of the multitude, but at the private good of the ruler, it will be an unjust and perverted rulership.
"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."
"Human knowledge, even at its peak, is like a shadow when compared to the light of the divine essence. We struggle to understand the order of the universe, and we are often baffled by the complexities of providence because we see only a fragment of the whole."
"Therefore, essence is what is signified by the definition of a thing. But it is clear that for all things whose essence is distinct from their existence, their existence must be caused by something else. For nothing can be the cause of its own existence, if existence is something caused, since then it would exist before it had existence, which is impossible."
"In order that there be generation three things are required: being in potency which is matter, non-existence in act which is privation, and that through which something comes to be in act which is form." (Aquinas, c. 1255/1952)
"Anyone who thinks that he understands the divine scriptures or any part of them, but cannot by his understanding build up the double love of God and neighbour, has not yet understood them as he ought." (De doctrina christiana, 1.36.40)
"Because the Trinity is ineffable, it is more true to say what it is not than what it is; for our words are but mirrors that break the light of the divine essence into fragments." (De Trinitate, 5.1.1)
"Two loves have built two cities: the love of self, even to the contempt of God, the earthly city; and the love of God, even to the contempt of self, the heavenly city." (De civitate Dei, 14.28)
"Evil is not a substance, but a perversion of the will which turns away from the higher things to the lower." (De libero arbitrio, 2.19)