1003 a I. Ἔστιν ἐπιστήμη τις ἣ θεωρεῖ τὸ ὂν ᾗ ὄν καὶ τὰ τούτῳ ὑπάρχοντα καθ᾿ αὑτό. αὕτη δ᾿ ἐστὶν οὐδε- μιᾷ τῶν ἐν μέρει λεγομένων ἡ αὐτή· οὐδεμία γὰρ τῶν ἄλλων ἐπισκοπεῖ καθόλου περὶ τοῦ ὄντος 25 ᾗ ὄν, ἀλλὰ μέρος αὐτοῦ τι ἀποτεμόμεναι περὶ τούτου θεωροῦσι τὸ συμβεβηκός, οἷον αἱ μαθη- ματικαὶ τῶν ἐπιστημῶν. ἐπεὶ δὲ τὰς ἀρχὰς καὶ τὰς ἀκροτάτας αἰτίας ζητοῦμεν, δῆλον ὡς φύσεώς τινος αὐτὰς ἀναγκαῖον εἶναι καθ᾿ αὑτήν. εἰ οὖν καὶ οἱ τὰ στοιχεῖα τῶν ὄντων ζητοῦντες ταύτας 30 τὰς ἀρχὰς ἐζήτουν, ἀνάγκη καὶ τὰ στοιχεῖα τοῦ ὄντος εἶναι μὴ κατὰ συμβεβηκός, ἀλλ᾿ ᾗ ὄν1· διὸ καὶ ἡμῖν τοῦ ὄντος ᾗ ὂν τὰς πρώτας αἰτίας ληπτέον.
II. Τὸ δὲ ὂν λέγεται μὲν πολλαχῶς, ἀλλὰ πρὸς ἓν καὶ μίαν τινὰ φύσιν, καὶ οὐχ ὁμωνύμως ἀλλ᾿ 35 ὥσπερ καὶ τὸ ὑγιεινὸν ἅπαν πρὸς ὑγίειαν, τὸ μὲν τῷ φυλάττειν, τὸ δὲ τῷ ποιεῖν, τὸ δὲ τῷ σημεῖον 1003 bεἶναι τῆς ὑγιείας, τὸ δ᾿ ὅτι δεκτικὸν αὐτῆς· καὶ τὸ ἰατρικὸν πρὸς ἰατρικήν (τὸ μὲν γὰρ τῷ ἔχειν τὴν ἰατρικὴν λέγεται ἰατρικόν, τὸ δὲ τῷ εὐφυὲς εἶναι πρὸς αὐτήν, τὸ δὲ τῷ ἔργον εἶναι τῆς ἰατρικῆς), ὁμοιοτρόπως δὲ καὶ ἄλλα ληψόμεθα λεγόμενα 5 τούτοις. οὕτω δὲ καὶ τὸ ὂν λέγεται πολλαχῶς
I. There is a science which studies Being qua Book iv. The Scope of Metaphysics. Being, and the properties inherent in it in virtue of its own nature. This science is not the same as any of the so-called particular sciences, for none of Metaphysics studies Being qua Being. the others contemplates Being generally qua Being; they divide off some portion of it and study the attribute of this portion, as do for example the mathematical sciences. But since it is for the first2 principles and the most ultimate causes that we are searching, clearly they must belong to something in virtue of its own nature. Hence if these principles were investigated by those also who investigated the elements of existing things, the elements must be elements of Being not incidentally, but qua Being. Therefore it is of Being qua Being that we too must grasp the first causes.
II. The term “being” is used in various senses, all the senses of the term “being” refer to substance; therefore we but with reference to one central idea and one definite characteristic, and not as merely a common epithet, Thus as the term “healthy” always relates to health (either as preserving it or as producing it or as indicating it or as receptive of it), and as “medical”2 relates to the art of medicine (either as possessing it must study the principles of substance. or as naturally adapted for it or as being a function of medicine)—and we shall find other terms used similarly to these—so “being” is used in various senses,3