  Material nature does not contain goodness; it can only be found in the human mind. Nature is depicted as a mechanical machine and should be studied by the natural sciences. Abstract economic theory is the mechanical analogy of these natural sciences: it is restricted to an investigation of the social world as a mechanical machine, and no ethical or religious considerations are taken into account. Jevons refutes the claims of some “sentimental writers” who regard economics as a “dismal science”, because its scope is restricted to wealth. These authors depict economics as a mechanical and miserable body of theories, whereas they hold true that a moral science should be concerned with sympathies, feelings and duties. Jevons uses an analogy from the natural sciences to refute this opinion: division of labour implies that some people investigate the mechanical aspects of iron, while other researchers devote their time to the study of its electrical or magnetic aspects. A physician may conclude that the health of a particular person will be fostered if he goes to the sea, but this person may decide otherwise by taking other considerations into account. This is the position of economics: charity for humanitarian reasons remains possible, but abstract economic theory shows that this may endanger future accumulation of wealth (Black 1977d, pp. 7–8).