As far as I understand, the ancient concept of government, as stated, for example, by Cicero, revolves around the enforcement of the law, enacting a just law, and obedience to the law. For example, a quotation from Cicero:
You understand, then, that the function of a magistrate is to govern, and to give commands which are just and beneficial and in conformity with the law. For as the laws govern the magistrate, so the magistrate governs the people, and it can truly be said that the magistrate is a speaking law, and the law a silent magistrate.
I am sure that other writers such as Plato and Aristotle talk along that line as well.
However, in the present day, the concept of government is more than just about "the law". Indeed, a modern government has judicial and legislative functions, which is similar to, "magistrate" that Cicero mentioned. Nevertheless, the executive usually also functions like a giant corporation that manages utilities, infrastructure, pension fund, currency rates, etc.
It seems to me that there is a gap between the two concepts. So, my questions are: First, when did the concept of government become more than just about "the law"? Secondly, why did the concept change?