Do not attempt great social or economic change suddenly.  Human life is an endless change of the factors of life unified by the stability of the unchanging personality.  The leaders of a civilization must keep pace with scientific advances to avoid taking the risk of being delayed.  Modern man is confronted with the task of making more readjustments of human values in one generation than have been made in two thousand years. 
Although the survival of a society depends chiefly on the progressive evolution of its mores this does not mean that each separate and isolated change in the composition of human society has been for the better.