scientific principle that he is to pay a just price, and, without being able precisely to ascertain the limits of such a price, will nevertheless strive to attain the closest possible approximation to them. A practically serviceable approximation he _can_ obtain. It is easier to determine scientifically what a man ought to have for his work, than what his necessities will compel him to take for it. His necessities can only be ascertained by empirical, but his due by analytical, investigation. In the one case, you try your answer to the sum like a puzzled schoolboy--till you find one that fits; in the other, you bring out your result within certain limits, by process of calculation. [40] Under the term "skill" I mean to include the united force of experience, intellect, and passion in their operation on manual labour: and under the term "passion," to include the entire range and agency of the moral feelings; from the simple patience and gentleness of mind which will give continuity and fineness to the touch, or enable one person to work without fatigue, and with good effect, twice as long as another, up to the qualities of character which render science possible--(the retardation of science by envy is one of the most tremendous losses in the economy of the present century)--and to the incommunicable emotion and imagination which are the first and mightiest sources of all value in art. It is highly singular that political economists should not yet have perceived, if not the moral, at least the passionate element, to be an inextricable quantity in every calculation. I cannot conceive, for instance, how it was possible that Mr. Mill should have followed the true clue so far as to write,--"No limit can be set to the importance--even in a purely productive and material point of view--of mere thought," without seeing that it was logically necessary to add also, "and of mere feeling." And this the more, because in his first definition of labour he includes in the idea of it "all feelings of a disagreeable kind connected with the employment of one's thoughts in a particular occupation." True; but why not also, "feelings of an agreeable kind?" It can hardly be supposed that the feelings which retard labour are more essentially a part of the labour than those which accelerate it. The first are paid for as pain, the second as power. The workman is merely indemnified for the first; but the second both produce a part of the exchangeable value of the work, and materially increase its actual quantity.