controversy alter their bearing; parties rise and fall around it; dangers and hopes appear in new relations; and old principles reappear under new forms. It changes with them in order to remain the same. In a higher world it is otherwise, but here below to live is to change, and to be perfect is to have changed often. SECTION II. ON THE KINDS OF DEVELOPMENT IN IDEAS. To attempt an accurate analysis or complete enumeration of the processes of thought, whether speculative or practical, which come under the notion of development, exceeds the pretensions of an Essay like the present; but, without some general view of the various mental exercises which go by the name we shall have no security against confusion in our reasoning and necessary exposure to criticism. 1. First, then, it must be borne in mind that the word is commonly used, and is used here, in three senses indiscriminately, from defect of our language; on the one hand for the process of development, on the other for the result; and again either generally for a development, true or not true, (that is, faithful or unfaithful to the idea from which it started,) or exclusively for a development deserving the name. A false or unfaithful development is more properly to be called a corruption. 2. Next, it is plain that _mathematical_ developments, that is, the system of truths drawn out from mathematical definitions or equations, do not fall under our present subject, though altogether analogous to it. There can be no corruption in such developments, because they are conducted on strict demonstration; and the conclusions in which they terminate, being necessary, cannot be declensions from the original idea. 3. Nor, of course, do _physical_ developments, as the growth of animal or vegetable nature, come into consideration here; excepting that, together with mathematical, they may be taken as illustrations of the general subject to which we have to direct our attention. 4. Nor have we to consider _material_ developments, which, though effected by human contrivance, are still physical; as the development, as it is called, of the national resources. We speak, for instance, of Ireland, the United States, or the valley of the Indus, as admitting of a great development; by which we mean, that those countries have fertile tracts, or abundant products, or broad and deep rivers, or central positions for commerce, or capacious and commodious harbours, the materials and instruments of wealth, and these at present turned to insufficient account. Development in this case will proceed by establishing marts, cutting canals, laying down railroads, erecting factories, forming docks, and similar works, by which the natural riches of the country may be made to yield the largest return and to exert the greatest influence. In this sense, art is the development of nature, that is, its adaptation to the purposes of utility and beauty, the human intellect being the developing power. 2.