Thus, nearly all the favors which governments confer on trade and manufactures, are contrary even to sound policy or justice; and, judging of them by the law of profit and loss, we should infer, that all this attention, bestowed by government on trade, had done more ill than good. But political economy is, in great part, a moral science. After having calculated the interests of men, it ought also to foresee what will act upon their passions. Ruled, as they are, by self-interest, pointing out their advantage will not be sufficient to determine their pursuit of it.