is still the common practice of the East. The muscular exertion, however, which it required, was very severe and exhausting, insomuch that it was often selected as a punishment for slaves who had offended their masters. When the time came at which the labour and sufferings of slaves were thought worth economizing, the greater part of this bodily exertion was rendered unnecessary, by contriving that the upper stone should be made to revolve upon the lower, not by human strength, but by the force of the wind or of falling water. In this case, natural agents, the wind or the gravitation of the water, are made to do a portion of the work previously done by labour.
§ 2.Cases like this, in which a certain amount of labour has been dispensed with, its work being devolved upon some natural agent, are apt to suggest an erroneous notion of the comparative functions of labour and natural powers; as if the co-operation of those powers with human industry were limited to the cases in which they are made to perform what would otherwise be done by labour; as if, in the case of things made (as the phrase is) by hand, nature only furnished passive materials. This is an illusion. The powers of nature are as actively operative in the one case as in the other. A workman takes a stalk of the flax or hemp plant, splits it into separate fibres, twines together several of these fibres with his fingers, aided by a simple instrument called a spindle; having thus formed a thread, he lays many such threads side by side, and places other similar threads directly across them, so that each passes alternately over and under those which are at right angles to it; this part of the process being facilitated by an instrument called a shuttle. He has now produced a web of cloth, either linen or sackcloth, according to the material. He is said to have done this by hand, no natural force being supposed to have acted in concert with him. But by what force is each step of this operation rendered possible, and the web, when produced,
