METAPHYSICS substance such as horse or gold are called ‘sortal ideas’: collections of simple co-occurent ideas plus the confused idea of the unknown substratum Particular substances are concrete individuals belonging to these diVerent sorts or species The substances of diVerent sorts have essences: to be a man, or to be an oak, is to have the essence of man or the essence of oak But there are, for Locke, two kinds of essence: real and nominal The real essence is: ‘The real, internal, but generally in substances, unknown constitution of things, whereon their discoverable Qualities depend.’ The nominal essence is the collection of simple ideas that have been assembled and attached to names in order to rank things into sorts or species The nominal essence gives the right to bear a particular name, and nominal essences are largely the arbitrary creation of human language In the case of a triangle, the real essence and the nominal essence (threesided Wgure) are the same Not so in the case of substances Locke considers the gold ring on his Wnger: It is the real constitution of its insensible Parts, on which depend all those Properties of Colour, Weight, Fusibility, Fixedness etc which are to be found in it Which Constitution we know not; and so having no particular Idea of it, have no Name that is the sign of it But yet it is its Colour, Weight, Fusibility and Fixedness etc which makes it to be Gold, or gives it a right to that Name, which is therefore its nominal Essence Since nothing can be called Gold, but what has a conformity of Qualities to that abstract complex Idea, to which that Name is annexed (E, 419) The real essences of things, like the hidden constitution of gold, are generally unknown to us Even in the case of a human being we have no more idea of his real essence than a peasant has of the wheels and springs which make a church clock strike (E 440) Essences belong to sorts, not individuals Individuals have neither real nor nominal essences ‘Nothing I have’, Locke says, ‘ is essential to me An accident or Disease, may very much alter my Colour, or Shape; a Fever, or Fall, may take away my Reason, or Memory, or both; and an Apoplexy leave neither Sense, nor Understanding no nor Life’ (E, 440) The real Locke, it seems to follow, is the underlying, impenetrable, substratum of various properties; something quite other than a human being Locke maintains that substance itself is indescribable because it is propertyless But it seems incredible that someone should argue that substance 189