Negative quantities occur in economics, as in other sciences, when a variable, passing through zero, becomes less than nothing, so that the addition thereof causes not augmentation but diminution. Most economic quantities are susceptible of this change of sign. Thus wealth, affected with the minus sign, becomes debt. The utility attending the consumption of wealth being taken as positive, the disutility of labour incurred by the production of wealth must be regarded as negative. Consumption is negative production. Jevons proposes to employ discommodity to signify any substance or action which is the opposite of commodity, that is to say, anything which we desire to get rid of, like ashes or sewage (Theory, 2nd edn, p. 63). Such an article may be said to have negative value. Among articles which have a negative value agents of production may occur. The loss attending the use of old-fashioned machinery and plant may be considered as a negative ‘quasi-rent’ (Marshall). It is conceivable that, capital becoming superabundant, borrowers would pay a ‘negative interest’, that is, receive a payment for safeguarding and keeping up the capital borrowed (Prof. Foxwell, ‘The Social Aspect of Banking’, Journal of the Institute of Bankers, vol. vii. p. 71, 1886). The practical limit to this class of payment would be soon attained. The payment which a waiter makes in order to be allowed to serve in a fashionable restaurant where there is a prospect of gratuities might be described as negative wages.