Commodity fetishism provides an example of what Engels called "false consciousness", which relates closely to the understanding of ideology. By "ideology", Marx and Engels meant ideas that reflect the interests of a particular class at a particular time in history, but which contemporaries see as universal and eternal. Marx and Engels's point was not only that such beliefs are at best half-truths, as they serve an important political function. Put another way, the control that one class exercises over the means of production include not only the production of food or manufactured goods but also the production of ideas (this provides one possible explanation for why members of a subordinate class may hold ideas contrary to their own interests). An example of this sort of analysis is Marx's understanding of religion, summed up in a passage from the preface to his 1843 "Contribution to the Critique of Hegel's Philosophy of Right":