8。Anotherkindoflabour，usuallyclassedasmental，but
conducingtotheultimateproductasdirectly，thoughnotso
immediately，asmanuallabouritself，isthelabourofthe
inventorsofindustrialprocesses。Isay，usuallyclassedas
mental，becauseinrealityitisnotexclusivelyso。Allhuman