"A science only advances with certainty, when the plan of inquiry and the object of our researches have been clearly defined; otherwise a small number of truths are loosely laid hold of, without their connexion being perceived, and numerous errors, without being enabled to detect their fallacy."

“What is the motive which operates in every man's breast to counteract the impulse towards the gratification of his wants and appetites?”

“The command of a large sum is a dangerous temptation to a national administration. Though accumulated at their expense, the people rarely, if ever profit by it: yet in point of fact, all value, and consequently, all wealth, originates with the people.”

“One product is always ultimately bought with another, even when paid for in the first instance with money.”

“In times of political confusion, and under an arbitrary government, many will prefer to keep their capital inactive, concealed, and unproductive, either of profit or gratification, rather than run the risk of its display. This latter evil is never felt under a good government.”

“How many other opinions, as universally prevailing and as much respected, will in like manner pass away?”

“Wherefore it is impossible to succeed in comparing wealth of different eras or different nations. This, in political economy, like squaring the circle in mathematics, is impracticable, for want of a common mean or measure to go by.”