Thus the labour of a manufacture adds, generally, to the value of the materials which he works upon, that of his own maintenance, and of his masters profits. The labour of a menial servant, on the contrary, adds to the value of nothing.
Good roads, canals, and navigable rivers, by diminishing the expence of carriage, put the remote parts of the country more nearly upon a level with with those of the neighbourhood of the town. They are upon that the greatest of all improvements.