As we need marks for SENSATIONS, we need marks also for IDEAS. The Ideas which we have occasion to name, are first, Simple Ideas, the copies of simple sensations; secondly, Complex Ideas, the copies of several sensations, combined. Of those complex ideas, also, there is one species, those copied directly from sensations, in the formation of which the mind has exercised but little control; as the ideas of rose, horse, stone, and of what are called the objects of sense in general. There is another species of complex ideas which, though derived also from the senses, are put together in a great degree at our discretion, as the ideas of a {138} centaur, a mountain of gold, of comfort, of meanness; all that class of ideas in short which Mr. Locke has called mixed modes. We may thus distinguish three classes of ideas, which we have occasion to name: 1, simple ideas, the copies of single sensations: 2, complex ideas, copied directly from sensations: 3, complex ideas, derived indeed from the senses, but put together in arbitrary combinations. The two former classes may be called Sensible, the last Mental Ideas. With respect to ideas, of the first two classes, those which are the direct copies of our sensations, either singly, or in groups; it is of great importance to observe, and also to remember, that, for the most part, the words, which are employed as marks of the Sensations, are made to serve the further purpose of being marks also of the Ideas. The same word is at once the name of the sensations, and the ideas. If any person were asked, whether the word BEING is the name of a Sensation, or of an Idea; he would immediately reply, that it is the name of an Idea. In like manner, if he were asked, whether the word ANIMAL is the mark of a cluster of Sensations, or of a cluster of Ideas; he would with equal readiness say, of a cluster of Ideas. But if we were to ask, whether the name Sheep is the name of a cluster of Sensations, or of a cluster of Ideas; he would probably say, that Sheep is the name of Sensations; in the same manner as rose, or apple. Yet, what is the difference? Only this, that ANIMAL is the more general name, and includes sheep along with other species; and that BEING is still more general, and includes animal along with vegetable, mineral, and other {139} _genera_. If sheep, therefore, or stone, be a name of sensations, so is animal or being; and if animal, or being, be a name of ideas, so is sheep or stone a name of ideas. The fact is, they are all names of both. They are names of the Sensations, primarily; but are afterwards employed as names also of the Ideas or copies of those sensations.