In such countries, though wages may sometimes rise a little in the neighbourhood of a great town, or wherever else there is an extraordinary demand for labour, and sink gradually as the distance from such places increases, till they fall back to the common rate of the country; yet we never meet with those sudden and unaccountable differences in the wages of neighbouring places which we sometimes find in England, where it is often more difficult for a poor man to pass the artificial boundary of a parish, than an arm of the sea, or a ridge of high mountains, natural boundaries which sometimes separate very distinctly different rates of wages in other countries.