Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
The "laws of king Italus," which were still applied in the time of Aristotle, may denote the institutions essentially common to both. These laws must have provided for the maintenance of peace and the execution of justice within the community, for military organization and martial law in reference to its external relations, for its government by a patriarchal chief, for a council of elders, for assemblies of the freemen capable of bearing arms, and for some sort of constitution. Judicial procedure (-crimen-, --krinein--, expiation (-poena-, --poinei--), retaliation (-talio-, --talao--, --tleinai--, are Graeco-Italian ideas. The stern law of debt, by which the debtor was directly responsible with his person for the repayment of what he had received, is common to the Italians, for example, with the Tarentine Heracleots. The fundamental ideas of the Roman constitution--a king, a senate, and an assembly entitled simply to ratify or to reject the proposals which the king and senate should submit to it--are scarcely anywhere expressed so distinctly as in Aristotle's account of the earlier constitution of Crete.
The germs of larger state-confederacies in the political fraternizing or even amalgamation of several previously independent stocks (symmachy, synoikismos) are in like manner common to both nations. The more stress is to be laid on this fact of the common foundations of Greek and Italian polity, that it is not found to extend to the other Indo-Germanic stocks; the organization of the Germanic community, for example, by no means starts, like that of the Greeks and Romans, from an elective monarchy. But how different the polities were that were constructed on this common basis in Italy and Greece, and how completely the whole course of their political development belongs to each as its distinctive property, (10) it will be the business of the sequel to show.
10. Only we must, of course, not forget that like pre-existing conditions lead everywhere to like institutions. For instance, nothing is more certain than that the Roman plebeians were a growth originating within the Roman commonwealth, and yet they everywhere find their counterpart where a body of -metoeci- has arisen alongside of a body of burgesses. As a matter of course, chance also plays in such cases its provoking game.
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Reference address : https://www.ellopos.net/elpenor/rome/1-02-earliest-migrations-italy.asp?pg=24