This citation is quoted by Kautsky in his "Ethics and the Materialist Conception of History" (pages 139–40 English Translation). The animal's actions are dependent upon visual motives, it is only by these that it sees, hears or observes in any other way. We can always tell what induced the animal to do this or the other act, for we, too, can see it if we look. With man, however, it is entirely different. We can not foretell what he will do, for we do not know the motives that induce him to act; they are thoughts in his head. Man considers, and in so doing, all his knowledge, the result of former experience, comes into play, and it is then that he decides how to act. The acts of an animal depend upon immediate impression, while those of man depend upon abstract conceptions, upon his thinking and perceiving. Man is at the same time influenced by finer invisible motives. Thus all his movements bear the impress of being guided by principles and intentions which give them the appearance of independence and obviously distinguishes them from those of animals.
Owing to their having bodily wants, men and animals are forced to seek to satisfy them in the natural objects surrounding them. The impression on the mind is the immediate impulse and beginning; the satisfaction of the wants is the aim and end of the act. With the animal, action follows immediately after impression. It sees its prey or food and immediately it jumps, grasps, eats, or does that which is necessary for grasping, and this is inherited as an instinct. The animal hears some hostile sound, and immediately it runs away if its legs are so developed to run quickly, or lies down like dead so as not to be seen if its color serves as a protector. Between man's impressions
