This question of the distinction between act and object in our apprehending of things is vitally important, since our whole power of acquiring knowledge is bound up with it. The faculty of being acquainted with things other than itself is the main characteristic of a mind. Acquaintance with objects essentially consists in a relation between the mind and something other than the mind; it is this that constitutes the mind’s power of knowing things. If we say that the things known must be in the mind, we are either unduly limiting the mind’s power of knowing, or we are uttering a mere tautology. We are uttering a mere tautology if we mean by “ in the mind” the same as by “ before the mind,” i.e. if we mean merely being apprehended by the mind. But if we mean this, we shall have to admit that what, in this sense , is in the mind, may nevertheless be not mental. Thus when we realize the nature of knowledge, Berkeley’s argument is seen to be wrong in substance as well as in form, and his grounds for supposing that “ideas”⁠—