Every farmer needs to distinguish, and distinguish carefully, the actual, necessary machinery of trade and the principles underlying it, that he may appreciate the genuine and oppose the false. On this account several chapters are given to questions of exchange, with an effort to bring into more prominent light the ways in which all commerce affects the farmer’s life. Chapter IX. Value The Basis Of Exchange. _The nature of value._—Perhaps no question in the discussion of wealth is of greater importance than the nature of value. Certainly the measurement of value in all our property is the basis of all exchanges, of all book accounts, and of all inventories. The worth of any piece of property in such estimates always involves some comparison, either of things possessed or of exertion required or of satisfaction yielded. In comparing an apple and a peach, both equally attainable, we may value the peach most highly because it gratifies desires in higher degree. Thinking of future uses, we may value the apple more highly because it will keep longer, and so be available for future wants. In considering all the kinds of satisfaction to be provided for, we may think of the peach as desired by more people who are likely to render us service, and therefore more readily exchangeable, and so of higher value. Again, the peach may be at the top of the tree and the apple within reach, in which case we may think whether the peach will give enough greater satisfaction to make it worth the greater exertion to get it. In this way a single individual, who has wants to be gratified only by exertion, forms an idea of value as founded upon some relation between his wants and his powers, between the desires to be gratified and the qualities of the object expected to give satisfaction. Since wealth always implies an accumulated store of good things, every one comes to think of the worth of his accumulation as estimated by what it will do at any time, in any place, in satisfying any need. So, most naturally, we associate our ideas of value with trade. An exchange of horses brings in not only the present qualities of each horse for present service, but all the qualities and circumstances affecting the possibilities of disposing of the horse whenever something else is needed more. An expert judge of horses not only knows when the horse is sound in wind and limb, and what are the signs of docility, speed, etc., but also what the rest of the world considers the qualities of a satisfactory horse. In all experience peculiar circumstances, varying the relation between wants and satisfaction, affect immensely our estimate of value. When an ancient king shouted, “My kingdom for a horse!” he was doubtless moved by the uselessness of a kingdom to one about to lose his life in battle for want of a horse and also by the difficulty at that particular moment of gaining a horse.