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
Lastly civic equality was in a certain sense undoubtedly attained or rather restored by the reform of 387, and the development of its legitimate consequences. As formerly, when the patricians still in fact formed the burgesses, these had stood upon a footing of absolute equality in rights and duties, so now in the enlarged burgess-body there existed in the eye of the law no arbitrary distinctions.
The gradations to which differences of age, sagacity, cultivation, and wealth necessarily give rise in civil society, naturally also pervaded the sphere of public life; but the spirit animating the burgesses and the policy of the government uniformly operated so as to render these differences as little conspicuous as possible. The whole system of Rome tended to train up her burgesses on an average as sound and capable, but not to bring into prominence the gifts of genius.
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/2-03-equalization-orders-aristocracy.asp?pg=33