This amalgamation of two substantially similar commonwealths produced rather an increase in the size than a change in the intrinsic character of the existing community. A second process of incorporation, which was carried out far more gradually and had far deeper effects, may be traced back, so far as the first steps in it are concerned, to this epoch; we refer to the amalgamation of the burgesses and the metoeci. At all times there existed side by side with the burgesses in the Roman community persons who were protected, the "listeners" (clientes), as they were called from their being dependents on the several burgess-households, or the "multitude" (plebes, from pleo, plenus), as they were termed negatively with reference to their want of political rights[1]. The elements of this intermediate stage between the freeman and the slave were, as has been shown[2] already in existence in the Roman household: but in the community this class necessarily acquired greater importance de facto and de jure, and that from two reasons. In the first place the community might itself possess half-free clients as well as slaves; especially after the conquest of a town and the breaking up of its commonwealth it might often appear to the conquering community advisable not to sell the mass of the burgesses formally as slaves, but to allow them the continued possession of freedom de facto, so that in the capacity as it were of freedmen of the community they entered into relations of clientship whether to the clans, or to the king. In the second place by means of the community and its power over the individual burgesses, there was given the possibility of protecting the clients against an abusive exercise of the dominium still subsisting in law. At an immemorially early period there was introduced into Roman law the principle on which rested the whole legal position of the metoeci, that, when a master on occasion of a public legal act - such as in the making of a testament, in an action at law, or in the census - expressly or tacitly surrendered his -dominium-, neither he himself nor his lawful successors should ever have power arbitrarily to recall that resignation or reassert a claim to the person of the freedman himself or of his descendants. The clients and their posterity did not by virtue of their position possess either the rights of burgesses or those of guests: for to constitute a burgess a formal bestowal of the privilege was requisite on the part of the community, while the relation of guest presumed the holding of burgess-rights in a community which had a treaty with Rome. What they did obtain was a legally protected possession of freedom, while they continued to be de jure non-free. Accordingly for a lengthened period their relations in all matters of property seem to have been, like those of slaves, regarded in law as relations of the patron, so that it was necessary that the latter should represent them in processes at law; in connection with which the patron might levy contributions from them in case of need, and call them to account before him criminally. By degrees, however, the body of metoeci outgrew these fetters; they began to acquire and to alienate in their own name, and to claim and obtain legal redress from the Roman burgess-tribunals without the formal intervention of their patron.
In matters of marriage and inheritance, equality of rights with the burgesses was far sooner conceded to foreigners[3] than to those who were strictly non-free and belonged to no community; but the latter could not well be prohibited from contracting marriages in their own circle and from forming the legal relations arising out of marriage - those of marital and paternal power, of agnatio and gentilitasof heritage and of tutelage - after the model of the corresponding relations among the burgesses.
Similar consequences to some extent were produced by the exercise of the ius hospitii, in so far as by virtue of it foreigners settled permanently in Rome and established a domestic position there. In this respect the most liberal principles must have prevailed in Rome from primitive times. The Roman law knew no distinctions of quality in inheritance and no locking up of estates. It allowed on the one hand to every man capable of making a disposition the entirely unlimited disposal of his property during his lifetime; and on the other hand, so far as we know, to every one who was at all entitled to have dealings with Roman burgesses, even to the foreigner and the client, the unlimited right of acquiring moveable, and (from the time when immoveables could be held as private property at all) within certain limits also immoveable, estate in Rome. Rome was in fact a commercial city, which was indebted for the commencement of its importance to international commerce, and which with a noble liberality granted the privilege of settlement to every child of an unequal marriage, to every manumitted slave, and to every stranger who surrendering his rights in his native land emigrated to Rome.
At first, therefore, the burgesses were in reality the protectors, the non-burgesses were the protected; but in Rome as in all communities which freely admit settlement but do not throw open the rights of citizenship, it soon became a matter of increasing difficulty to harmonize this relation de jurewith the actual state of things. The flourishing of commerce, the full equality of private rights guaranteed to all Latins by the Latin league (including even the acquisition of landed property), the greater frequency of manumissions as prosperity increased, necessarily occasioned even in peace a disproportionate increase of the number of metoeci. That number was further augmented by the greater part of the population of the neighbouring towns subdued by force of arms and incorporated with Rome; which, whether it removed to the city or remained in its old home now reduced to the rank of a village, ordinarily exchanged its native burgess-rights for those of a Roman metoikos. Moreover the burdens of war fell exclusively on the old burgesses and were constantly thinning the ranks of their patrician descendants, while the metoeci shared in the results of victory without having to pay for it with their blood.