_On Instinct in Connection with the Understanding._
It is evident, that the definition of a Genus or class is an _adequate_ definition only of the lowest _species_ of that Genus: for each higher species is distinguished from the lower by some additional character, while the general definition includes only the characters common to _all_ the species. Consequently it _describes_ the lowest only. Now I distinguish a genus or _kind_ of Powers under the name of Adaptive power, and give as its generic definition--the power of selecting, and adapting means to proximate ends; and as an instance of the lowest _species_ of this genus, I take the stomach of a caterpillar. I ask myself, under what words I can generalize the action of this organ; and I see, that it selects and adapts the appropriate means (that is, the assimilable part of the vegetable _congesta_) to the proximate end, that is, the growth or reproduction of the insect's body. This we call VITAL POWER, or _vita propria_ of the stomach; and this being the _lowest_ species, its definition is the same with the definition of the _kind_.
Well! from the power of the stomach, I pass to the power exerted by the whole animal. I trace it wandering from spot to spot, and plant to plant, till it finds the appropriate vegetable; and again on this chosen vegetable, I mark it seeking out and fixing on the part of the plant, bark, leaf, or petal, suited to its nourishment: or (should the animal have assumed the butterfly form), to the deposition of its eggs, and the sustentation of the future _larva_. Here I see a power of selecting and adapting means to proximate ends _according to circumstances_: and this higher species of Adaptive Power we call INSTINCT.
Lastly, I reflect on the facts narrated and described in the preceding extracts from Hüber, and see a power of selecting and adapting the proper means to the proximate ends, according to _varying_ circumstances. And what shall we call this yet higher species? We name the former, Instinct: we must call this INSTINCTIVE INTELLIGENCE.
Here then we have three Powers of the same kind; Life, Instinct, and instinctive Intelligence: the essential characters that define the genus existing equally in all three. But in addition to these, I find one other character common to the highest and lowest: namely, that the purposes are all manifestly predetermined by the peculiar organization of the animals; and though it may not be possible to discover any such immediate dependency in all the actions, yet the actions being determined by the purposes, the _result_ is equivalent: and both the actions and the purposes are all in a necessitated reference to the preservation and continuance of the particular animal or the progeny. There is selection, but not _choice_: volition rather than will. The possible _knowledge_ of a thing, or the desire to have that _thing_ representable by a distinct correspondent _thought_, does not, in the animal, suffice to render the thing an _object_, or the ground of a purpose. I select and adapt the proper means to the separation of a stone from a rock, which I neither can, or desire to make use of, for food, shelter, or ornament: because, perhaps, I wish to measure the angles of its primary crystals, or, perhaps, for no better reason than the apparent _difficulty_ of loosening the stone--_sit pro ratione voluntas_--and thus make a motive out of the absence of all motive, and a reason out of the arbitrary will to act without any reason.