Chapter 5 — Causes and predication

Therefore, now that we have seen that there are four causes—the efficient, formal, material and final—we must note that any of these causes can be spoken of in many ways. We call one thing a prior cause and another a posterior cause. For example, we say that art and the doctor are the cause of health, but art is a prior cause and the doctor is a posterior cause. And it is similar in the formal cause and in the other causes. Notice, also that we must always bring the question back to the first cause. For example, if it be asked: Why is this man healthy? we would answer: Because the doctor has healed him. Likewise, if it be asked: Why did the doctor heal him? we would say: Because of the art of healing which the doctor has.

Notice, also, that the proximate cause is the same as the posterior cause and that the remote cause is the same as the prior cause. Hence these two divisions of causes into prior and posterior, remote and proximate signify the same thing. Moreover, it must be observed that that which is more universal is always called the remote cause, but that which is more particular is called the proximate cause. For example, we say that the proximate form of man is his definition, namely, rational animal; but animal is more remote and substance is still more remote. All superiors are forms of the inferiors. Again, the proximate matter of the statue is bronze, but the remote matter is metal, and the still more remote is body.

Further, there is one cause which is an essential cause, another which is accidental. An essential cause is said of one which is the cause of something as such: for example, the builder is the cause of the house and the wood is the matter of the bench. An accidental cause is said of one which happens to an essential cause. For example, we say that ‘the grammarian builds’; the grammarian is called the cause of the building accidentally, not insofar as he is a grammarian, but insofar as it happens to the builder that he is a grammarian; and it is similar in other causes.

Likewise, some causes are simple, others are composed. A cause is simple when that alone is said to be the cause which is the essential cause, or that alone which is the accidental cause; as if we were to say that the builder is the cause of the house and likewise if we were to say that the doctor is the cause of the house. A cause is composed when both are said to be the cause, as if we were to say that the medical builder is the cause of the house. According to the explanation of Avicenna, that can be called a simple cause also which is a cause without the addition of another. For example, bronze is the cause of the statue without the addition of another matter, because the statue is made of bronze; and we say that the doctor causes health or that fire heats. But a cause is composed when many things must come together in order that there be a cause. For example, not one man, but many, are the cause of the motion of a ship; and not one stone, but many, are the cause of a house.

Again, some causes are in act, others are in potency. A cause in act is one which causes a thing in act, as the builder while he is building or the bronze when a statue is made of it. A cause in potency is one which, although it does not cause a thing in act, can cause it nevertheless, such as a builder when he is not building. Note that in speaking of causes in act, the cause and the thing caused must exist at the same time, so that if one exists the other does also. If there is a builder in act, he must be building and, if there is building in act, it is necessary that there be a builder in act. But this is not necessary in causes which are only in potency.

Moreover, it should be noted that the universal cause is compared to the universal thing that is caused and the singular cause is compared to the singular thing that is caused. For example, we say that a builder is the cause of a house and that this builder is the cause of this house.