person would single out a class of heavenly bodies to call by such a name; many races have never formed the conception. To those who gained learning enough, the meaning was further enriched by connection with the Ptolemaic system of cycles and epicycles. Then, as by a touch, Copernicus altered the whole aspect of the word, and changed the classification which it represented, ejecting the sun and moon, and taking in the earth. And all this is now used to help give shape to the at first dim and formless idea, which the language-learner is made to entertain along with the sign which is taught him. Once more, the child is made to count, and in the process his conceptions of number are cast into a decimal shape, one in which each higher factor is made up of ten of the next lower, till he comes to feel that such tenfoldness is a natural characteristic of enumeration. Yet, if we inquire whence comes this particular shape, we find it growing out of the simple fact that we have two hands, with five fingers on each! So utterly extraneous and accidental a cause as this, as turned to account by the simple races who laid the deep foundations of our mathematics, determines the "inner form" assumed by the mathematical conceptions of each new member of our race; of course, quite without his knowledge.
So it is all the way through language. Along with and by means of words, the young learner is made to take in the ideas which the knowledge and experience of older men have shaped; he accepts the current classifications and abstractions of his community, at first only imperfectly, then with fuller and more independent action of his own, till finally he grows up to the stature of his language, and has, at least in some departments, nothing more to learn of those about him. At the beginning, and in less degree later, he was so hurried on by the superiority of his instructors in knowledge and mental development, that he had neither leisure nor inclination to be original; now he becomes in his turn a teacher, and also a shaper. By his action and that of his fellows, the common instrument of expression undergoes a constant slow change. Their new knowledge has somehow to be worked in. It is done partly, as in the case of planet by reshaping the conceptions contained in old words, and shifting the boundaries of old classifications; partly by the cognition of new particulars which are brought under old names, expanding so far their contents—as when Uranus and Neptune are brought into the class of planets, and the satellites of Jupiter and Saturn make a class for the formerly unique appellation moon; and partly by providing new names for objects, products, qualities, relations, before unperceived, or so dimly apprehended as not to seem to call for expression. And the provision is made in part by deliberately going to other tongues and borrowing material from them (so Uranus, Neptune), or else by forming new compounds of native material (so steamboat, railroad), or, very frequently, by mere transfer of old words to new uses, substituted or ad-
