Whether the descriptive process is more necessary than the process that assigns causes.
One inquires further as to which process is more necessary.
And it seems to be the descriptive process. Because principles and suppositions are considered through description, and conclusions are considered through the assignment of causes. Since, then, principles are more necessary than conclusions, a knowledge [ cognitio] of principles is more necessary than a knowledge of conclusions; this is why, etc.
In addition, "it is necessary that the one learning believe," according to the Philosopher in the On Sophistical Refutations. But this is only the case if the descriptive mode is necessary, and therefore, etc.
The Philosopher says the opposite. For he says that the descriptive process is for the sake of teaching or for the sake of the one teaching, but the process that assigns causes is for the sake of both. Therefore, the second is more necessary.
To this, one must reply that in one way the first process is more necessary, and in another way the other is. The second process is more necessary for an advanced audience but the descriptive process is more necessary to those who are less advanced. In fact, the natural process is from cause to effect, and for learning about a particular thing the natural order is first to propose a conclusion and second to prove it, and this is why, speaking naturally, the descriptive process is prior, and the other process is second. And because a first thing can exist without a later thing, the first process is therefore more necessary, since knowledge can be introduced through description without knowledge of the cause; but knowledge of the cause cannot exist without some description, because it cannot be introduced without a supposition of the principle, and this is why, etc.
Which cause the natural philosopher ought to consider more.
On the supposition that the natural philosopher considers all causes, one next asks which cause he should consider more.
1. And it seems it should be the material cause. Because the natural philosopher has especially to consider motion, and matter is the principle of transmutation. Since, then, matter is especially the principle of transmutation, he especially has to consider matter.
2. In addition, "logic and physics define things differently," according to the Philosopher in the book On the Soul, because logic defines through form, and physics defines through matter. But one should particularly consider the cause by means of which one defines. Therefore, etc.
On the contrary. According to the Philosopher in the second book of the Metaphysics, the principles of being and of knowing are the same. But form is more the principle of being, and also, therefore, of knowing. But physics has to consider a principle like this more, and therefore, etc.
Moreover, the Philosopher proves that he has to consider the final cause first, because each thing depends on its end.
One must reply that physics has to consider all causes, although it has to consider diverse causes in diverse respects. For if a thing is considered with respect to its generation, then physics especially has to consider the material and efficient causes because these causes are presupposed for generation. If, how-
ever, a thing is considered with respect to its essence, then physics most especially has to consider the formal cause. If, however, a thing is considered with respect to its operation and property, then physics especially has to consider the final cause. And because in this book the Philosopher inquires into the properties and operations of animals, he therefore principally considers the final cause here.
1. To the first argument one must reply that the principle of transmutation can be either active or passive. Thus, although matter is particularly the passive principle of transmutation, it is not the active principle, and this is why, etc.
2. To the second argument one must reply that logic defines by means of the parts of the definition [ratio], that is, by means of genus and differentia, and each of these is received from the form. And this is why it is said to define according to the form. But the natural philosopher defines by means of the parts of the essence, and considers something only in terms of its relation to matter. Therefore, in the book On the Soul he makes a determination about the soul only insofar as it is the act of a physical body. And this is why he is said to define by means of the matter, because he defines by means of the parts integrating the essence.
-  "Physics": physicus. In fact, the Latin does not denote the discipline, but its practitionernot physics, but the natural philosopher engaged in the study of physical nature. Here and later, however, we will regularly translate these and related nouns (physicus, metaphysicus, etc.) as denoting the discipline, in order to clarify the differences between these divisions of philosophy. Likewise, logicus, a logician, is translated as "logic."