In the first supposition, it is the head of the master which conducts the labour of the slave, and turns it towards ingenuity: in the second, every head is at work, and every hand is improving in dexterity. Where hands therefore are principally necessary, the slaves have the advantage; where heads are principally necessary, the advantage lies in favour of the free. Set a man to labour at so much a day, he will go on at a regular rate, and never seek to improve his method: let him be hired by the piece, he will find a thousand expedients to extend his industry. This is exactly the difference between the slave and the free man. From this I account for the difference between the progress of industry in antient and modern times. Why was a _peculium_ given to slaves, but to engage them to become dextrous? Had there been no _peculium_ and no _libertini_, or free men, who had been trained to labour, there would have been little more industry any where, than there was in the republic of Lycurgus, where, I apprehend, neither the one or the other was to be found. I return. When once this revolution is brought about; when those who formerly lived in simplicity become industrious; matters put on a new face. Is not this operation quite similar to that represented in the fifth chapter of the first book? There I found the greatest difficulty, in shewing how the mutual operations of supplying food and other wants could have the effect of promoting population and agriculture, among a people who were supposed to have no idea of the system proposed to be put in execution. Here the plan appears familiar and easy. The difference between them seems to resemble that of a child’s learning a language by grammar, or learning it by the ear in the country where it is spoken. In the first case, many throw the book aside, but in the other none ever fail of success. I have said, that matters put on a new face; that is to say, we now find two trading nations instead of one, with this difference, however, that as hitherto we have supposed the merchants all in one interest, the compound demand, that is, the competition of the buyers, has been, and must still continue on the side of the natives. This is a great prejudice to their interest, but as it is not supposed sufficient to check their industry, nor to restrain their consumption of the manufactures, let me here examine a little more particularly the consequences of the principle of demand in such a situation; for although I allow, that it can never change sides, yet it may admit of different modifications, and produce different effects, as we shall presently perceive.