of fact it is impossible to deny _in thought_ the reality of substance, or to think at all without it, however philosophers may have denied it _in language_,—or thought that they denied it when they only rejected some erroneous or indefensible meaning of the term. 60. THE ARISTOTELIAN CATEGORIES.—The first palpable distinction we observe in the data of experience is that between _substance_ and _accident_. “We might naturally ask,” writes Aristotle,(218) “whether what is signified by such terms as _walking_, _sitting_, _feeling well_, is a being (or reality).... And we might be inclined to doubt it, for no single one of such acts _exists by itself_ (καθ᾽ αὐτὸ πεφυκός), no one of them is separable from _substance_ (οὐσία); it is rather to _him who_ walks, or sits, or feels well, that we give the name of _being_. That which is a being _in the primary meaning of this term_, a being _simply and absolutely_, and not merely a being _in a certain sense_, or with a qualification, is substance—ὡστε τὸ πρώτως ὂν καὶ οὐ τὶ ὂν ἀλλ᾽ ὂν ἁπλῶς ἡ οὐσία ἂν εἴν.”(219) But manifestly, though substances, or what in ordinary language we call “persons” and “things”—men, animals, plants, minerals—are real beings in the fullest sense, nevertheless sitting, walking, thinking, willing, and actions generally, are also undoubtedly realities; so too are states and qualities; and shape, size, posture, etc. And yet we do not find any of these latter actually existing in themselves like substances, but only dependently on substances—on “persons” or “things” that think or walk or act, or are large or small, hot or cold, or have some shape or quality. They are all _accidents_, in contradistinction to substance.