This strong connection between thoughts, language, and tools, each of which is impossible without the other, shows that they must have developed at the same time. How this development took place, we can only conjecture. Undoubtedly it was a change in the circumstances of life that changed men from our ape-like ancestors. Having migrated from the woods, the original habitat of apes, to the plain, man had to undergo an entire change of life. The difference between hands and feet must have developed then. Sociability and the ape-like hand, well adapted for grasping, had a due share in the new development. The first rough objects, such as stones or sticks, came to hand unsought, and were thrown away. This must have been repeated so often that it must have left an impression on the minds of those primitive men. To the animal, surrounding nature is a single unit, of the details of which it is unconscious. It can not distinguish between various objects. Our primitive man, at his lowest stage, must have been at the same level of consciousness. From the great mass surrounding him, some objects (tools) come into his hands which he used in procuring his existence. These tools, being very important objects, soon were given some designation, were designated by a sound which at the same time named the particular activity. Owing to this sound, or designation, the tool and the particular kind of activity stands out from the rest of the surroundings. Man begins to analyze the world by concepts and names, self-consciousness makes its appearance, artificial objects are purposely sought and knowingly made use of while working. This process――for it is a very slow process――marks the beginning of our becoming men. As soon as men deliberately seek and apply certain tools, we can say that these are being developed; from this stage to the manufacturing of tools, there is only one step. The first crude tools differ according to use; from the sharp stone we get the knife, the bolt, the drill, and the spear; from the stick we get the hatchet. With the further differentiation of tools, serving later for the division of labor, language and thought develop into richer and newer forms, while thought leads man to use the tools in a better way, to improve old and invent new ones. So we see that one thing brings on the other. The practice of sociability and the application to labor are the springs in which technique, thought, tools and science have their origin and continually develop. By his labor, the primitive ape-like man has risen to real manhood. The use of tools marks the great departure that is ever more widening between men and animals. IX. ANIMAL ORGANS AND HUMAN TOOLS.