De Rervm Natvra Constantivm Scientia, Principiis Et Affectionibvs Commvnibvs, Dispvtatio

XIII. It is consistent with this that it should be contained within one object, of which it treats and by which it is distinguished from other sciences. For since defining a science by one object is nothing other than saying that the abstraction by which the science is directed toward the knowledge of its things is of one genus, and that the things known by the same abstraction are referred either as species, or as principles, or as passions to some common thing contained by the same abstraction—which is then called the object—if Physics uses one and the same abstraction in its perception of things, it must have one set object.

XIV. Nor should it disturb anyone that several conditions are usually attributed to an object in common usage. For from this description of the object, all other things and many others are gathered: for example, that the object is not said of all things comprehended by science; that the object of attribution and the object of properties are not the same; that it is not necessary that general properties be assigned concerning the object of attribution taken generally; that diverse objects of attribution can be assigned in the same science; and finally, that it is not necessary that the subject of attribution be posited by the science. And that which is said, that the subject is posited by the science, must be understood concerning the subject of properties.

XV. With these things as it were anticipated, the object of natural philosophy is natural being or a natural body, as it is natural. This is clear because, besides the fact that it is the adequate object of the abstraction that Physics uses, all things that are involved in the same abstraction are referred to it. For it is sensible and depends on matter since it moves, and it comprehends all sensible substances, so that rightly all things are recalled to it as principles, species, and passions.

XVI. We have used the gemination repetition, when we said "natural, as it is natural," because from the same thing that is a natural being, different concepts can be formed that are held by different abstractions. Thus, it can happen that other sciences treat of the same thing about which natural philosophy treats, but never with the same concept or cognition. As this is not absurd—when we know things by an inadequate and not absolute cognition, but by a relative one, by which they are compared to different things—so the gemination was not to be omitted.