“How do you know but ev’ry Bird that cuts the airy way Is an immense world of delight, clos’d by your senses five?” --BLAKE. “_Ils n’ont pas de cerveau--ils n’ont que de l’âme._” A dog was being described, with all his emotion, his apparent passion to make himself understood, his failure to reach comprehension; and that was how the French man of letters summed up the brute creation--“_pas de cerveau--que de l’âme_.” Nor is it a paradox: it is a half-truth that is more than half true--more true at least than its converse, which many hold. There is a large school to-day who assert that animals are “mere machines.” Machines they may be: it is the qualification which does not fit. I suppose that by saying “mere” machines it is meant to imply that they have the soulless, steely quality of a machine which goes when it is set going, stops when another lever is turned, acts only in obedience to outer stimuli, and is in fact unemotional--a bundle of operations without any quality meriting the name of a self. It is true that the further we push our analysis of animal behaviour, the more we find it composed of a series of automatisms, the more we see it rigorously determined by combination of inner constitution and outer circumstance, the more we have cause to deny to animals the possession of anything deserving the name of reason, ideals, or abstract thought. The more, in fact, do they appear to us as mechanisms (which is a much better word than machines, since this latter carries with it definite connotations of metal or wood, electricity or steam). They are mechanisms, because their mode of operation is regular; but they differ from any other type of mechanism known to us in that their working is--to put it in the most non-committal way--accompanied by emotion. It is, to be sure, a combination of emotion with reason that we attribute to a soul; but none the less, in popular parlance at least, the emotional side is predominant, and pure reason is set over against the emotional content which gives soul its essence. And this emotional content we most definitely find running through the lives of higher animals. The objection is easily and often raised that we have no direct knowledge of emotion in an animal, no direct proof of the existence of any purely mental process in its life. But this is as easily laid as raised. We have no direct knowledge of emotion or any other conscious process in the life of any human being save our individual selves; and yet we feel no hesitation in deducing it from others’ behaviour. Although it is an arguable point whether biological science may not for the moment be better served by confining the subject-matter and terms of analysis to behaviour alone, it is a very foolhardy “behaviorist” indeed who denies the _existence_ of emotion and conscious process!