We have now, finally, to consider how it arises that the instincts of any animal species are so similar within the limits of that species—a circumstance which has not a little contributed to the engrafted-mechanism theory. But it is plain that like causes will be followed by like effects; and this should afford sufficient explanation. The bodily mechanism, for example, of all the individuals of a species is alike; so again are their capabilities and the outcomes of their conscious intelligence—though this, indeed, is not the case with man, nor in some measure even with the highest animals; and it is through this want of uniformity that there is such a thing as individuality. The external conditions of all the individuals of a species are also tolerably similar, and when they differ essentially, the instincts are likewise different—a fact in support of which no examples are necessary. From like conditions of mind and body (and this includes like predispositions of brain and ganglia) and like exterior circumstances, like desires will follow as a necessary logical consequence. Again, from like desires and like inward and outward circumstances, a like choice of means—that is to say, like instincts—must ensue. These last two steps would not be conceded without restriction if the question were one involving conscious deliberation, but as these logical consequences are supposed to follow from the unconscious, which takes the right step unfailingly without vacillation or delay so long as the premises are similar, the ensuing desires and the instincts to adopt the means for their gratification will be similar also. Thus the view which we have taken concerning instinct explains the very last point which it may be thought worth while to bring forward in support of the opinions of our opponents. I will conclude this chapter with the words of Schelling: “Thoughtful minds will hold the phenomena of animal instinct to belong to the most important of all phenomena, and to be the true touchstone of a durable philosophy.” Chapter IX Remarks upon Von Hartmann’s position in regard to instinct. UNCERTAIN how far the foregoing chapter is not better left without comment of any kind, I nevertheless think that some of my readers may be helped by the following extracts from the notes I took while translating. I will give them as they come, without throwing them into connected form. * * * * * Von Hartmann defines instinct as action done with a purpose, but without consciousness of purpose.