This sophism in its more general form may make little impression, but applied to a particular order of facts, to a certain branch of industry, to a given class, of producers, it is extremely specious; and this is easily explained. It forms a syllogism which is not _false_, but _incomplete_. Now, what is _true_ in a syllogism is always and necessarily present to the mind. But _incompleteness_ is a negative quality, an absent _datum_, which it is very possible, and indeed very easy, to leave out of account. Man produces in order to consume. He is at once producer and consumer. The reasoning which I have just explained considers him only in the first of these points of view. Had the second been taken into account, it would have led to an opposite conclusion. In effect, may it not be said:-- The consumer is richer in proportion as he _purchases_ all things cheaper; and he purchases things cheaper in proportion to their abundance; therefore it is abundance which enriches him. This reasoning, extended to all consumers, leads to the _theory of plenty_. It is the notion of _exchange_ imperfectly understood which leads to these illusions. If we consider our personal interest, we recognise distinctly that it is double. As _sellers_ we have an interest in dearness, and consequently in scarcity; as _buyers_, in cheapness, or what amounts to the same thing, in the abundance of commodities. We cannot, then, found our reasoning on one or other of these interests before inquiring which of the two coincides and is identified with the general and permanent interest of mankind at large.