This practice, seen in its purity in the seventeenth century especially, was markedly different from the practices of other colonies in the settlement of their back lands. For during most of the period New England did not use her wild lands, or public domain, as a source of revenue by sale to individuals or to companies, with the reservation of quit-rents; nor attract individual settlers by "head rights," or fifty-acre grants, after the Virginia type; nor did the colonies of the New England group often make extensive grants to individuals, on the ground of special services, or because of influence with the government, or on the theory that the grantee would introduce settlers on his grant. They donated their lands to groups of men who became town proprietors for the purpose of establishing communities. These proprietors were supposed to hold the lands in trust, to be assigned to inhabitants under restraints to ensure the persistence of Puritan ideals. During most of the seventeenth century the proprietors awarded lands to the new-comers in accordance with this theory. But as density of settlement increased, and lands grew scarce in the older towns, the proprietors began to assert their legal right to the unoccupied lands and to refuse to share them with inhabitants who were not of the body of proprietors. The distinction resulted in class conflicts in the towns, especially in the eighteenth century,[75:1] over the ownership and disposal of the common lands. The new settlements, by a process of natural selection, would afford opportunity to the least contented, whether because of grievances, or ambitions, to establish themselves. This tended to produce a Western flavor in the towns on the frontier. But it was not until the original ideals of the land system began to change, that the opportunity to make new settlements for such reasons became common. As the economic and political ideal replaced the religious and social ideal, in the conditions under which new towns could be established, this became more possible. Such a change was in progress in the latter part of the seventeenth century and during the eighteenth. In 1713, 1715, and 1727, Massachusetts determined upon a policy of locating towns in advance of settlement, to protect her boundary claims. In 1736 she laid out five towns near the New Hampshire border, and a year earlier opened four contiguous towns to connect her Housatonic and Connecticut Valley settlements.[76:1] Grants in non-adjacent regions were sometimes made to old towns, the proprietors of which sold them to those who wished to move.