To sum up and to generalize: we may say that the causes of the decay of the Roman family life were very complex, and that this is true of nearly all important social changes. It is impossible to reduce the causes of these changes to any single principle or set of causes. While we have seen that changes in economic conditions were undoubtedly very influential in bringing about the profound changes in the Roman family, still we have no ground for regarding the economic changes as determinative of all the rest. We know as yet little of the development of industry in antiquity. What little we do know, however, furnishes good ground for claiming that changes in the methods of getting a living are among the most influential causes of social change in general; but there is nothing which warrants the sweeping generalization of Karl Marx and his followers, "that the method of the production of the material life determines the social, political, and spiritual life process in general." On the contrary, the evolution of the Roman family clearly shows moral and psychological factors at work quite independent of economic causes. The decay of ancestor worship, for example, cannot be wholly attributed to the change in the method of getting a living. The very growth of population and accompanying changes in political conditions probably had quite as much to do with the undermining of ancestor worship. Moreover, while religion may not be an original determining cause of social forms, it is, nevertheless, as we have already seen, especially that which gives them stability and permanency, so much so that the life history of a culture is frequently the life history of a religion. The decay of religious ideas and beliefs, therefore, from any cause, frequently proves the important element working for social change in all societies. So, too, changes in political conditions, especially changes in law through new legislation, frequently prove a profound modifying influence in societies. Lastly, there are certain moral causes inherent in the individual, oftentimes involving perverted expressions of instinct, which lead to profound social changes. Such was the vice which Rome copied very largely from Greece, but which proved the final solvent in its family life.