14. Let us take a piece of wax and without letting it go out of our hands paint it different colors successively, subject it to different degrees of temperature, softening it by warming, and then cooling it; let us give it different forms, of a globe, a cylinder, a parallelopipedon, a table, a vase, or a statue; do all these changes take place in the same thing? Yes. Is this thing not a color, or a figure, or a degree of temperature? No; because all these qualities were and ceased to be whilst the thing remained the same. How do I know that the thing remained the same? Because there was a continuity of sensation in the eye fixed upon the object; in the touch which, although it felt the modifications of warm and cold, hard and soft, experienced also an uninterrupted sensation of an object, which remained constantly in the hand, and the weight of which was continuously felt. Therefore there is something there which is not the modifications, but is that which is modified, something common to them all, which receives and connects them, outside of me and within me. 15. Examining one conception of this permanent something, we find that, after abstracting its qualities, we have: I. The idea of being. We say the thing, the something, the subject, etc., we therefore speak of a being, of a quality. Without the reality there is nothing; and nothing cannot be the subject of modifications, or the link connecting impressions. II. The idea of being, which we here find, is not pure, it is not being alone. The qualities exist, are beings, and still we do not confound them with the subject. III. That which accompanies the idea of being is the idea of permanence amidst succession, and the relation of this permanence as the point of connection, the immovable centre in the midst of succession. 16. If, therefore, we wished to define substance, we could only say that it is _a permanent being in which occur the changes which are presented to us in the sensible phenomena_. Our knowledge is all reduced to this; all that we can add beside, is only hypothesis or conjecture. In vain you ask me, what is this being? Give me the intuition of the essence of corporeal things, and I will tell you; but while I know them only by their effects, that is, the impressions which they produce in me, I cannot answer you. I know that it is something; I know its relation to its forms; I know that the forms are in the subject, and are not the subject; but here is the limit of my knowledge. The object corresponding to the idea composed of a permanent being and its relation to various forms is what I call corporeal substance.