Pleasure and pain are the only motives taken account of in political economy in so far as ‘it makes entire abstraction of every other passion or motive but the desire for wealth; except those which may be regarded as perpetually antagonizing principles to the desire of wealth, namely, aversion to labour and desire of the present enjoyment of costly indulgences’ (Mill, Unsettled Questions, p. 138). This abstraction, legitimate within limits, is liable to be strained too far in several directions.