You will think perhaps of atoms of the elements as instances of identically similar things, but these are things not of experience but of theory, and there is not a phenomenon in chemistry that is not equally well explained on the supposition that it is merely the immense quantities of atoms necessarily taken in any experiment that mask by the operation of the law of averages the fact that each atom also has its unique quality, its special individual difference. This idea of uniqueness in all individuals is not only true of the classifications of material science; it is true, and still more evidently true, of the species of common thought, it is true of common terms. Take the word chair. When one says chair, one thinks vaguely of an average chair. But collect individual instances, think of armchairs and reading chairs, and dining-room chairs and kitchen chairs, chairs that pass into benches, chairs that cross the boundary and become settees, dentists' chairs, thrones, opera stalls, seats of all sorts, those miraculous fungoid growths that cumber the floor of the Arts and Crafts Exhibition, and you will perceive what a lax bundle in fact is this simple straightforward term. In co-operation with an intelligent joiner I would undertake to defeat any definition of chair or chairishness that you gave me. Chairs just as much as individual organisms, just as much as mineral and rock specimens, are unique things—if you know them well enough you will find an individual difference even in a set of machine-made chairs—and it is only because we do not possess minds of unlimited capacity, because our brain has only a limited number of pigeon-holes for our correspondence with an unlimited universe of objective uniques, that we have to delude ourselves into the belief that there is a chairishness in this species common to and distinctive of all chairs.