I have hitherto carefully restricted myself, in speaking of exchange, to the use of the term "advantage;" but that term includes two ideas: the advantage, namely, of getting what we _need_, and that of getting what we _wish for_. Three-fourths of the demands existing in the world are romantic; founded on visions, idealisms, hopes, and affections; and the regulation of the purse is, in its essence, regulation of the imagination and the heart. Hence, the right discussion of the nature of price is a very high metaphysical and psychical problem; sometimes to be solved only in a passionate manner, as by David in his counting the price of the water of the well by the gate of Bethlehem; but its first conditions are the following:--The price of anything is the quantity of labour given by the person desiring it, in order to obtain possession of it. This price depends on four variable quantities. _A_. The quantity of wish the purchaser has for the thing; opposed to [Greek: a], the quantity of wish the seller has to keep it. _B_. The quantity of labour the purchaser can afford, to obtain the thing; opposed to [Greek: b], the quantity of labour the seller can afford, to keep it. These quantities are operative only in excess; _i.e._, the quantity of wish (_A_) means the quantity of wish for this thing, above wish for other things; and the quantity of work (_B_) means the quantity which can be spared to get this thing from the quantity needed to get other things. Phenomena of price, therefore, are intensely complex, curious, and interesting--too complex, however, to be examined yet; every one of them, when traced far enough, showing itself at last as a part of the bargain of the Poor of the Flock (or "flock of slaughter"), "If ye think good, give ME my price, and if not, forbear"--Zech. xi. 12; but as the price of everything is to be calculated finally in labour, it is necessary to define the nature of that standard. Labour is the contest of the life of man with an opposite:--the term "life" including his intellect, soul, and physical power, contending with question, difficulty, trial, or material force. Labour is of a higher or lower order, as it includes more or fewer of the elements of life: and labour of good quality, in any kind, includes always as much intellect and feeling as will fully and harmoniously regulate the physical force. In speaking of the value and price of labour, it is necessary always to understand labour of a given rank and quality, as we should speak of gold or silver of a given standard. Bad (that is, heartless, inexperienced, or senseless) labour cannot be valued; it is like gold of uncertain alloy, or flawed iron.[54]