A tender mother, among the inferior ranks of people, is of afraid to send her son to school at a seaport town, lest the sight of the ships and the conversation and adventures of the sailors should entice him to go to sea. The distant prospect of hazards, from which we can hope to extricate ourselves by courage and address, is not disagreeable to us, and does not raise the wages of labour in any employment. It is otherwise with those in which courage and address can be of no avail. In trades which are known to be very unwholesome, the wages of labour are always remarkably high. Unwholesomeness is a species of disagreeableness, and its effects upon the wages of labour are to be ranked under that general head.

In all the different employments of stock, the ordinary rate of profit varies more or less with the certainty or uncertainty of the returns.