(_b_) This necessity becomes apparent from still another point of view. The estimate of a nation’s wealth should not be confined to one particular moment. It is not enough that the labour and economy of its citizens should at the present moment assure for it a great mass of exchange values. It is also necessary that these resources of labour and of economy should be safeguarded and that their future development should be assured, for “the power of creating wealth is infinitely more important than the wealth itself.” A nation should concern itself with the growth of what List in a vague fashion calls its productive forces even more than with the exchange values which depend upon them.[580] Even a temporary sacrifice of the second may be demanded for the sake of the first. In these expressions List merely wishes to emphasise the distinction between a policy which takes account of a nation’s future as compared with one which takes account only of the present. “A nation must sacrifice and give up a measure of material property in order to gain culture, skill, and powers of united production; it must sacrifice some present advantages in order to ensure to itself future ones.”[581] But what are these productive forces which constitute the permanent source of a nation’s prosperity and the condition of its progress? With particular insistence List first of all mentions the moral and political institutions, freedom of thought, freedom of conscience, liberty of the press, trial by jury, publicity of justice, control of administration, and parliamentary government. All these have a stimulating and salutary effect upon labour. He is never weary of recalling to mind the loss of wealth caused by the Revocation of the Edict of Nantes, or by the Spanish Inquisition, which, says he, “had passed sentence of death upon the Spanish navy long ere the English and the Dutch fleets had executed the decree” (p. 88). He unjustly[582] accuses Smith and his school of materialism, and condemns them for neglecting to reckon those infinitely powerful but perhaps less calculable forces.