of self-movement, and can only be brought to perfection in this connection. Also the power of the human faculties of cognition and human knowledge is most intimately bound up with human practice, as we shall see.
The practice it is, however, which guarantees to us the certainty of our knowledge. So soon as my knowledge enables me to bring about distinct effects the production of which lies in my power, the relation of cause and effect ceases for me to be simply chance or simple appearance, or simple forms of knowledge such as the pure contemplation and thought might well describe them. The knowledge of this relation becomes through the practice a knowledge of something real, and is thus raised to certain knowledge.
The boundaries of practice show certainly the boundaries of our certain knowledge. That theory and practice are dependent on one another, and only through the mutual permeation of the one by the other can at any time the highest results attainable be arrived at, is only an outcome of the fact that movement and intellectual powers from their earliest beginnings were bound to go together. In the course of the development of human society the duration of labour has brought it about that the natural unity of these two factors should be destroyed, and created classes to whom principally the movement, and others to whom principally the knowing, fell. We have already pointed out how this was reflected in philosophy through the creation of two worlds, a higher or intellectual and a lower or bodily. But naturally in no individual were the two functions ever to be wholly divided, and the proletariat movement of to-day is directing its energies with good effect to abolishing this distinction, and with it also the dualist philosophy, the philosophy of pure knowledge. Even the deepest, most abstract, knowledge, which apparently is farthest removed from the practical, influence this, and are influenced by it, and to bring in us this influence to consciousness becomes the duty of a critique of human knowledge. As before, knowledge remains in
