That which cannot be weighed against other things in a common price scale, many economists have argued, can have no place in Economics, because Economics is essentially a measuring science with price as its standard of measurement. No Socialist can properly accept this view. It may be quite impossible to prove by any quantitative assessment that, say, a decrease in working hours that has been accompanied by a fall in total output has been worth while because the human satisfactions of greater leisure outweigh the loss of goods ; but the lack of a comparative measuring-rod does not mean that it is possible to avoid weighing such things against each other, or that the one is a matter in which the economist should interest himself to the exclusion of the other. It would doubtless be much simpler if we could put everything to the test by means of a single kind of measurement, so as to be in a position to tell with certainty how to achieve the optimum total result. In the absence of such a standard we are not justified in dismissing from Economics everything that cannot be measured in terms of money payments. It is desirable and convenient to apply some method of measuring things whenever this can legitimately be done ; and it is very convenient to be in a position to compare one thing with another by using a common measuring-rod. But there are dangers that, in pursuit of these conveniences, we may attempt to measure what cannot really be measured at all, or apply inappropriate methods of measurement in order to bring disparate things to a common account.