The great legal cultures were built up around some general idea of what law should be like. For the Romans, Positive Law did not consist primarily in an arbitrary act of imposition of rules of conduct, but in a set of rules deriving from the very nature of social relations. For this reason the jurist Gaius (2nd century AD) could say that the first source of law is not statute but nature. Legal science itself is not knowledge of laws, but of things, i.e., of right things (iusti atque iniusti scientia), that is to say of the normality of social relations. Cicero in De Officiis explains the...