The Complete English Tradesman by Daniel Defoe

There is some difference between an honest man and an honest tradesman; and though the distinction is very nice, yet, I must say, it is to be supported. Trade cannot make a knave of an honest man, for there is a specific difference between honesty and knavery which can never be altered by trade or any other thing; nor can that integrity of mind which describes and is peculiar to a man of honesty be ever abated to a tradesman; the rectitude of his soul must be the same, and he must not only intend or mean honestly and justly, but he must do so; he must act honestly and justly, and that in all his dealings; he must neither cheat nor defraud, over-reach nor circumvent his neighbour, nor indeed anybody he deals with; nor must he design to do so, or lay any plots or snares to that purpose in his dealing, as is frequent in the general conduct of too many, who yet call themselves honest tradesmen, and would take it very ill to have any one tax their integrity.

But after all this is premised, there are some latitudes, like poetical licences in other cases, which a tradesman is and must be allowed, and which by the custom and usage of trade he may give himself a liberty in, which cannot be allowed in other cases to any man, no, nor to the tradesman himself out of his business -- I say, he may take some liberties, but within bounds; and whatever some pretenders to strict living may say, yet that tradesman shall pass with me for a very honest man, notwithstanding the liberty which he gives himself of this kind, if he does not take those liberties in an exorbitant manner; and those liberties are such as these.