But the explanation of heredium given above is by no means necessary; in fact the sources regard it not as the only private land, but rather as the smallest share allotted to any citizen, the rich and noble possessing more.[270] While accordingly the wealthy man owned many iugera, the poor man, limited to his heredium, was obliged to earn part of his living by labor as a tenant or as a wage-earner in the field of his rich neighbor;[271] and in the early colonies the bina iugera were granted on the same aristocratic principle. If this is the true explanation of heredium, the strongest argument in support of the theory of public ownership at Rome in the late regal period is taken away; we must either abandon the theory or relegate it to a time far anterior to the Servian reforms. Mommsen’s assumption[272] that the sixteen oldest rural tribes were instituted some time after the city tribes by the division of gentile lands is untenable on other grounds. The gens which gave its name to the tribe could not have owned all the land in the tribe; for in that case all but the sixteen gentes would have been landless. Again, assuming, as he does, that all the land belonged to the gentes, which he supposes to have been exclusively patrician, we should be forced to conclude that the division left the plebeians landless. And further, if we bear in mind that the gens developed from the family, we must also believe that the undivided gentile land was once a family estate, which according to Roman usage had to be registered in some tribe, even if the land of the gens was not so registered. Mommsen’s theory proves therefore not only to be unsupported by the sources but actually unthinkable. In conclusion we may safely say that though some land remained public, and though the gens after it had come into existence owned some common land, individual, or at most family,[273] ownership was in full force in the earliest times of which we have knowledge.