The Complete English Tradesman by Daniel Defoe

I have dwelt long upon the tradesman's management of himself, in order to his due preserving both his business and his reputation: let me bestow one chapter upon the tradesman for his conduct among his neighbours and fellow-tradesmen.

Credit is so much a tradesman's blessing that it is the choicest ware he deals in, and he cannot be too chary of it when he has it, or buy it too dear when he wants it; it is a stock to his warehouse, it is current money in his cash-chest, it accepts all his bills, for it is on the fund of his credit that he has any bills to accept; demands would else be made upon the spot, and he must pay for his goods before he has them -- therefore, I say, it accepts all his bills, and oftentimes pays them too; in a word, it is the life and soul of his trade, and it requires his utmost vigilance to preserve it.