Reason, in the sense in which it is here used, is found feebly in the oyster. Oysters taken from a depth never uncovered by the sea open their shells, lose their water, and quickly perish. But oysters taken from the same depths, if kept where they are occasionally left uncovered for short intervals, learn to keep their shells closed and to live a much longer period out of the water. On the coast of France ‘oyster schools’ exist, where oysters intended for inland cities are educated to keep their shells closed when out of the water in order to enable them to survive the desiccating exposures of the overland journey.[1] This act of the bivalve is probably the result of something like a vague form of reason. It is an act adapted to the accomplishment of a definite end, and the adapting power is acquired from experience. It is, moreover, reason which in its final analysis does not differ from the reason displayed by the wisest being that thinks. Judgment, forethought, common-sense, inference, ingenuity, genius, reason, and abstract thought, are all exercises of the cognitive or perceptive power of mind, and consist, all of them, in nothing more nor less than the discerning of relations among stimuli. The dog who adopts a cut-off in order to intercept a fleeing hare performs exactly the same kind of intellectual process as the mechanic who erects a windmill in order to divert the energies of the breeze, or the politician who adopts a particular platform to catch votes. ‘A perception is always in its essential nature what logicians term a _conclusion_, whether it has reference to the simplest memory of the past sensation or to the highest product of abstract thought. For, when the highest product of abstract thought is analysed, the ultimate elements must always be found to consist in material given directly by the senses; and every stage in the symbolic construction of ideas, in which the process of abstraction consists, depends on acts of perception taking place in the lower stages’.[5] The difference among the perceptive acts of different individuals consists, not in the different kinds of intellectual exercise, but in differences among the _materials_ with which the perceptive faculty deals. There are perceptions of simple sensations, and there are perceptions of composite sensations, or concepts—perceptions of elementary relations, and perceptions of compound and elaborate relations. But all displays of rational faculty, from the simple judgment of distance by the dimness and distinctness of definition and the size of the visual angle, which all higher animals are compelled to make, to the labyrinthic abstractions of the logician, consist in nothing in addition to discriminations among stimuli.