The days of the French Revolution and Republic saw many efforts to sweep away various trappings of the "Ancien Régime" (the old feudal monarchy); some of these were more successful than others. The new Republican government sought to institute, among other reforms, a new social and legal system, a new system of weights and measures (which became the metric system), and a new calendar. Amid nostalgia for the ancient Roman Republic, the theories of the Enlightenment were at their peak, and the devisers of the new systems looked to nature for their inspiration. Natural constants, multiples of ten, and Latin as well as Ancient Greek derivations formed the fundamental blocks from which the new systems were built.