motive, because it is an idea, yet it operates with the necessity of a stimulus, _i.e._, it cannot be resisted, but we must put the idea away in order to make it cease to affect us. This is also the case with disgusting things, which excite the desire to vomit. Thus we have treated the instinct of animals as an actual link, of quite a distinct kind, between movement following upon stimuli, and action following upon a known motive. Now we might be asked to regard breathing as another link of this kind. It has been disputed whether it belongs to the voluntary or the involuntary movements, that is to say, whether it follows upon motive or stimulus, and perhaps it may be explained as something which is between the two. Marshall Hall (“On the Diseases of the Nervous System,” § 293 sq.) explains it as a mixed function, for it is partly under the influence of the cerebral (voluntary), and partly under that of the spinal (non-voluntary) nerves. However, we are finally obliged to number it with the expressions of will which result from motives. For other motives, _i.e._, mere ideas, can determine the will to check it or accelerate it, and, as is the case with every other voluntary action, it seems to us that we could give up breathing altogether and voluntarily suffocate. And in fact we could do so if any other motive influenced the will sufficiently strongly to overcome the pressing desire for air. According to some accounts Diogenes actually put an end to his life in this way (Diog. Laert. VI. 76). Certain negroes also are said to have done this (F. B. Osiander “On Suicide” [1813] pp. 170-180). If this be true, it affords us a good example of the influence of abstract motives, _i.e._, of the victory of distinctively rational over merely animal will. For, that breathing is at least partially conditioned by cerebral activity is shown by the fact that the primary cause of death from prussic acid is that it paralyses the brain, and so, indirectly, restricts the breathing; but if the breathing be artificially maintained till the stupefaction of the brain has passed away, death will not ensue. We may also observe in passing that breathing affords us the most obvious example of the fact that motives act with just as much necessity as stimuli, or as causes in the narrowest sense of the word, and their operation can only be neutralised by antagonistic motives, as action is neutralised by re-action. For, in the case of breathing, the illusion that we can stop when we like is much weaker than in the case of other movements which follow upon motives; because in breathing the motive is very powerful, very near to us, and its satisfaction is very easy, for the muscles which accomplish it are never tired, nothing, as a rule, obstructs it, and the whole process is supported by the most inveterate habit of the individual. And yet all motives act with the same necessity. The knowledge that necessity is common to movements following upon motives, and those