[6] ... Past economic periods govern the activity of the individual...not only because they have taught him sternly what he has to do, but also for another reason. During every period the farmer must live, either directly upon the physical product of the preceding period or upon what he can obtain with the proceeds of this product. All the preceding periods have, furthermore, entangled him in a net of social and economic connections which he cannot easily shake off. They have bequeathed him definite means and methods of production. All these hold him in iron fetters fast in his tracks. ...