apprehension of which is nearly as old as humanity itself, which men learned to name as soon as they learned to talk at all, and whose names are not liable to pass away or become superseded. The words red, green, blue, yellow, or their equivalents, go back to the earliest period of human speech; it is when some new and delicate shades of colour, like the aniline dyes, are invented, that appellations must be sought for them, and may be found even among names of localities, as Magenta, Solferino, to which the circumstances of the time have given a sudden notoriety. Any two rustics, from the time of Adam to the present, could talk with one another, with all the particularity which their practical ends required, of earth and rock, of pebbles and stones, of sand and gravel, of loam and clay: but, since the beginning of the present century, the mineralogist and geologist have elicited a host of new facts touching the history and constitution of the earth's crust and the materials of which this is made up, have arranged and classified its strata and their contents, have brought to light numberless relations, of cause and effect, of succession, of origin, date, and value, which had hitherto lain hidden in it; and, to express these, they have introduced into English speech a whole technical vocabulary, and one which is still every year extending and changing. So it is with botany; so with metaphysics; so with every other branch of science and art. And though the greater part of the technical vocabularies remains merely technical, understood and employed only by special students in each branch, yet the common speech is not entirely unaffected by them. Some portion of the results of the advancement in knowledge made by the wise and learned reaches even the lowest, or all but the very lowest, and is expressed in their language; and it thus becomes a part of the fundamental stock of ideas which constitute the heritage of each generation, which every child is taught to form and use. Language, in short, is expanded and contracted in precise adaptation to the circumstances and needs of those who use it; it is enriched or impoverished, in every part, along with the enrichment or impoverishment of their minds.
This is, as I have said, the most noticeable mode of change