Summa Theologica

“It was necessary for man’s salvation that there should be a knowledge revealed by God, besides the philosophical sciences built up by human reason.” 

A clear expression of Aquinas’ belief in the complementarity of reason and faith. Faith, or revelation, perfects and builds upon reason and sense knowledge.

“The knowledge of God is naturally implanted in all.”

From Damascene. Aquinas goes on to clarify that we all have a “general and confused” perception of God’s existence, since this is necessary in order to set us on the path to seeking God as our ultimate happiness. However, to gain more clarity on the existence of God we must follow a reasoned argument. Aquinas therefore presents his Five Ways. 

“Thus, then, He wills both Himself to be, and other things to be; but Himself as the end, and other things as ordered to that end, in so far as it befits the divine goodness that other things should be partakers therein.”

A strong statement of Aquinas’ teleology and integrated medieval worldview, centered on God as the first cause and final end or fulfillment of the entire universe. 

“All knowledge comes about by some assimilation of the knower to the thing known.”

Aquinas’ epistemology (theory of how we come to know things) is heavily based on Aristotle. The process of knowing is compared to the impression of a seal upon wax, where the wax is the knowing faculty and the seal is the thing known. Thus, the act of knowledge consists in a sort of agreement or concordance between the intellect and the thing known. 

“Grace comes midway between nature and glory.”

Aquinas sees man’s spiritual journey as a three-stage process. Nature denotes the basic state of man as a creature of God, as described in Genesis. Grace is further given to man as a free gift of God, to help him love and serve God. Glory is man’s final destiny, when his entire nature—body and soul—will be raised up to a higher level in heaven. 

“We need not ask if the soul and body are one, as neither do we ask if wax and its shape are one.” 

This quote is from Aristotle’s On the Soul. Plato believed that the soul is imprisoned in the body and is destined to be released from it. Aristotle, by contrast, held that the two were naturally and inseparably united. Aquinas follows Aristotle’s thought on this matter, seeking to assimilate it to the Judeo-Christian view of the body as created by God and essentially good. For Aquinas, both body and soul are essential components of the human being. 

“In nature nothing is idle or purposeless.” 

For Aquinas, there is inherent design and purpose in the universe, because it was created by God who is eternal reason. Thus, everything exists for a reason and serves a purpose in God’s plan. The universe is founded on natural laws that human beings can discover through reason. This is a key Thomistic tenet expressing a teleology (theory of a purpose or goal in the universe). It contrasts with later views of the universe as the result of chance forces. 

“All natural things were produced by the Divine art, and so may be called God’s works of art.” 

One of a handful of passages in the Summa that have a bearing on aesthetics (the theory of beauty; see also Quote 21). Man resembles God in his power to create things, and thus by analogy we can understand God’s work by comparing it with human art. 

“Matter is for the sake of form, and not form for the sake of matter.”

Matter exists to serve the form which it defines and actualizes. Matter is like an instrument of the form. Thus, for example, the parts of the human body are proportioned and adapted to the various faculties and operations of the body. 

“Whereas the other animals take delight in the objects of the senses only as ordered to food and sex, man alone takes pleasure in the beauty of sensible objects for their own sake.” 

This quote comes during the discussion of the creation of man’s body. Man has a higher, spiritual nature that other animals lack. The structure of his body reflects this.

“Good is stronger than evil.”

For Aquinas, evil has no independent existence but is rather the corruption or privation of good. Evil in fact depends on good, preying upon it like a disease.  

“Enlightenment, properly speaking, is the manifestation of the truth in reference to God, Who enlightens every intellect.” 

Aquinas describes the initiating role that God takes in human knowledge. The quote contrasts notably with later ideas of enlightenment in Western culture (e.g., the Age of Enlightenment) which assign enlightenment to man’s own power of self. 

“That in which a man rests as in his last end is master of his affections, since he takes from this his entire rule of life.” 

The last end is the goal of human existence, the principle toward which we strive. Thus, whatever we choose as our last end is a moral choice that will affect our moral state and happiness. 

“Happiness is joy in truth.”

From Augustine. Joy is the consummation of happiness, in which the will rests content in the knowledge of truth. Thus, joy accompanies and perfects happiness. 

“Therefore, since happiness is nothing else but the attainment of the Sovereign Good, it cannot be without concomitant delight.” 

Delight or pleasure naturally accompanies happiness; Aquinas’ metaphor is that of heat accompanying fire. This statement shows that Aquinas accords a legitimate place to pleasure.

“To enjoy is to adhere lovingly to something for its own sake.”

From Augustine. To enjoy something is to rest contented in the knowledge of it. Thus, it belongs both to the apprehensive (knowing) as well as to the appetitive (desiring) faculties. We must first know something in order to desire it. 

“Sin is a word, deed, or desire, in opposition to the Eternal Law.” 

Sin consists in an action straying from the rightness of conforming to its proper end—namely, the fulfillment of God’s law, which we grasp through reason.

“Every privation of good, in whatever subject, is an evil; but sin consists properly in an action done for a certain end, and lacking due order to that end.”

Aquinas distinguishes between evil—which we suffer—and sin—which we perform. He seeks to define what the evil of a human action precisely consists of. An action is evil when it does not conform to right reason and its intended goal. 

“Who hurts the hand, hurts the man.” 

Man is a social being, and every individual is part of a society. Thus, every evil done to an individual has repercussions on the larger social order. Thus, human actions are to be judged as good or evil on this basis.

“All these emotions are right in those whose love is rightly placed…For they fear to sin, they desire to persevere; they grieve for sin, they rejoice in good works.”

From Augustine. We must strive to have right emotions, which are in conformity with true principles. Thus, passions like fear and desire, which have a tendency to evil, can be channeled to good ends.

“The beautiful is the same as the good, and they differ in aspect only. For since good is what all seek, that which calms the desire is implied in the notion of good, while that which calms the desire by being seen or known pertains to the notion of the beautiful.”

This quote resonates with the much later philosophical concept that truth and beauty are the same. Here Aquinas asserts that good and beauty are the same, but differ only in that beauty is a more specific aspect of the good—namely, that which pleases the senses. 

“When a man loves another with the love of friendship, he wills good to him, just as he wills good to himself; and so he apprehends him as his other self, in so far, namely, as he wills good to him as to himself.”

Love arises from a perceived union between the love and the thing loved. We apprehend that the thing is similar to us or contributes to our well-being. Thus, we love it as we love ourselves. 

“The beloved is contained in the lover by being impressed on his affection through a tranquil satisfaction. On the other hand, the lover is contained in the beloved because the lover penetrates, so to speak, into the beloved.” 

From Aquinas’ discussion of the effects of love. Aquinas describes love as a close and intimate union between two people

The passage strongly implies an acceptance and affirmation of human love as a good.