It is this consideration which gives the answer to the single sentence of J.S. Mill, which has been sometimes held to offer a complete refutation of the notion of an existing state of over-supply. "The error is in not perceiving that, though all who have an equivalent to give _might_ be fully provided with every conceivable article which they desire, the fact that they go on adding to the production proves that this is not actually the case."[161] Here the present desire to consume either what is produced or its equivalent is assumed to be the only motive which can lead an individual to produce. The fact that people go on producing is regarded as proof that they are not "fully provided with every conceivable article they desire." If this were true it would be a final and conclusive refutation of the idea of over-supply. But if saving means postponed consumption, and the desire to save, as well as the desire to consume, is a _vera causa_ in production, then the fact of continued production affords no proof that such production must be required to supply articles which are desired for consumption. Ultimately a belief that some one will consent to consume what is produced underlies the continued production of "a saving person," but, as we shall see presently, the belief of a competing producer that he can get a market for his goods, even when justified by events, is no guarantee against excessive production in the whole trade. If, then, those who have the power to consume in the present desire to postpone their consumption they will refuse to demand consumptive goods, and will instead bring into existence an excess of productive goods. § 10. The diagram on next page may serve more clearly to indicate the quantitative maladjustment of Consuming and Saving which constitutes under-consumption, and exhibits itself in a plethora of machinery and productive goods. [Illustration: MECHANISM OF PRODUCTION.]