Again, I suppose it will be further admitted that in the mind of animals and in the mind of infants there is a world of images standing as signs of outward objects; and that the only reason why these images are not attended to unless called up by the sensuous associations supplied by their corresponding objects, is because the mind is not yet able to leave the ground of such association, so as to move through the higher and more tenuous medium of introspective thought.[112] Nevertheless, this image world assuredly displays an internal activity which is not wholly dependent on sensuous associations supplied from without. That is to say, one image suggests another, this another, and so on—although, as I have just conceded, this cannot be due to successive acts of inward attention, or of the self-conscious contemplation of images known as such. Nevertheless, that an internal—though unintentional—play of ideation takes place in the minds of brutes, without the necessity of immediate associations supplied from present objects of sense, admits of being amply proved from the phenomena of dreaming, hallucination, home-sickness, pining for absent friends, &c., which, as I have fully shown in my previous work, can only be explained by recognizing such a play of inward ideation.[113] Now, I hold it of importance to note that such an internal play of ideation is thus possible even in the absence of self-consciousness, because many writers have assumed, without any justification, that unless ideas are intentionally contemplated as such, they must be wholly dependent for their occurrence upon associations supplied by present objects of sense. Of course I do not doubt that an agent who is capable of intentionally making one idea stand as the object of another, is likewise capable of going very much further than a brute in the way of causing one idea to start from another irrespective of immediate stimulation from without. My point here is merely to remark that the ideation of brutes is not wholly dependent on such stimulation; but is capable, in a certain humble degree, of forming independent chains of its own. The next thing which I desire to be remembered in connection with the ideation of brutes is, that it is not restricted to the mere reproduction in memory of particular objects of sensuous impressions; but, as we have so fully seen in Chapter III., admits of undergoing that amount of mental elaboration which belongs to what I have termed recepts.