Now that which takes place in the soul of an animal when hungry and seeking food is not an experience of this kind. The reason, therefore, which we have for saying of ourselves or our fellow-men that we desire food as an object of which we are conscious, does not apply to animals. Those animals indeed with which we chiefly associate, exhibit all the signs of impulses to action excited by recurrent images of pleasure previously experienced, but this recurrence of the image of a past pleasure does not in itself amount to the consciousness of a desired object consisting in a particular pleasure. Self-consciousness is implied in the one as it is not in the other. The mere revival in a sentient subject of the image of a past pleasure, with the consequent impulse after the renewal of the pleasure, does not imply any consciousness by the subject of itself in distinction from the pleasure, as the subject which has enjoyed it, and may enjoy it again, and which has also enjoyed other pleasures comparable with it; nor any consciousness of an objective world to which belongs the conditions of the pleasure--the means to it, and its consequences. (§ 122 ¶ 2)