It follows from what has been said, that all animals, even the least developed, have understanding; for they all know objects, and this knowledge determines their movements as motive. Understanding is the same in all animals and in all men; it has everywhere the same simple form; knowledge of causality, transition from effect to cause, and from cause to effect, nothing more; but the degree of its acuteness, and the extension of the sphere of its knowledge varies enormously, with innumerable gradations from the lowest form, which is only conscious of the causal connection between the immediate object and objects affecting it—that is to say, perceives a cause as an object in space by passing to it from the affection which the body feels, to the higher grades of knowledge of the causal connection among objects known indirectly, which extends to the understanding of the most complicated system of cause and effect in nature. For even this high degree of knowledge is still the work of the understanding, not of the reason. The abstract concepts of the reason can only serve to take up the objective connections which are immediately known by the understanding, to make them permanent for thought, and to relate them to each other; but reason never gives us immediate knowledge. Every force and law of nature, every example of such forces and laws, must first be immediately known by the understanding, must be apprehended through perception before it can pass into abstract consciousness for reason. Hooke’s discovery of the law of gravitation, and the reference of so many important phenomena to this one law, was the work of immediate apprehension by the understanding; and such also was the proof of Newton’s calculations, and Lavoisier’s discovery of acids and their important function in nature, and also Goethe’s discovery of the origin of physical colours. All these discoveries are nothing more than a correct immediate passage from the effect to the cause, which is at once followed by the recognition of the ideality of the force of nature which expresses itself in all causes of the same kind; and this complete insight is just an example of that single function of the understanding, by which an animal perceives as an object in space the cause which affects its body, and differs from such a perception only in degree. Every one of these great discoveries is therefore, just like perception, an operation of the understanding, an immediate intuition, and as such the work of an instant, an _apperçu_, a flash of insight. They are not the result of a process of abstract reasoning, which only serves to make the immediate knowledge of the understanding permanent for thought by bringing it under abstract concepts, _i.e._, it makes knowledge distinct, it puts us in a position to impart it and explain it to others. The keenness of the understanding in apprehending the causal relations of objects which are known indirectly,