It is just as true to say that we feel matter and not its force as it is to say that we feel force and not matter. Indeed, both are inseparable from the object, as we have already remarked. But by means of the faculty of thought we separate from the simultaneously and successively occurring phenomena the general and the concrete. For instance, we abstract the general concept of sight from the various phenomena of our sight and distinguish it by the name of power of vision from the concrete objects, or substances, of our eyes. From a multitude of sense perceptions we develop by means of reason the general element. The general element of different water phenomena, for instance, is the water power distinguished from the substance of the water. If levers of different materials but of the same length have the same power, it is plain that in this case force is different from matter only in so far as it represents the general element of various substances. A horse does not pull without force, and this force does not pull without the horse. Indeed, in practice the horse is force and force is the horse. But nevertheless we may distinguish the power of pulling from other qualities of the horse, or we may refer to the common element in different services of horses as general horse power, without thereby starting from any other hypothesis than we do in distinguishing the sun from the earth. For in reality the sun does not exist without the earth, nor the earth without the sun. The world of sense perceptions is made known to us only by our consciousness, but consciousness is conditioned on the world of sense perceptions. Nature is infinitely united or infinitely separated, according to whether we regard it from the standpoint of consciousness as an unconditional unit or from the standpoint of sense perceptions as an unconditional multiplicity. There is truth in both unity and multiplicity, but it is truth only relatively speaking, under certain conditions. It matters a great deal whether we look about with the eyes of the body or with the eyes of the mind. For the eyes of the mind, matter is force. For the eyes of the body, force is matter. The abstract matter is force, the concrete force is matter. Matter is represented by the objects of the hand, of practice, while force is an object of understanding, of science.