The economic basis of the unfortunate social changes which were associated with the process of enclosure came gradually to be recognized. It was evidently futile to enact laws requiring the cultivation of land "wasted and worn with continual plowing and thereby made bare, barren and very unfruitfull."[131] Merely restrictive and prohibitory legislation was followed by the suggestion of constructive measures. Until the middle of the sixteenth century, laws were made in the attempt to put a stop to the conversion of arable land to pasture under any conditions, and required that land which had been under cultivation should be plowed in the future. In the act of 1552, however, an attitude somewhat more reasonable is to be seen. It was provided that land which had been under cultivation within a certain number of years preceding the act should be tilled, "_or so much in quantity_."[132] Public men were also urging that less time be devoted to the futile attempt to force men to cultivate land unfit for tillage, and that encouragement be given instead to measures for improving the waste, and bringing fresh land under the plow.[133] After a time, moreover, another fact became apparent: there was a marked tendency to break up and again cultivate the land which in former generations had been converted to pasture. The statute of 1597 not only contained a proviso permitting the conversion of arable fields to pasture on condition that other land be tilled instead,[134] thus tacitly admitting that the reason for withdrawing land from cultivation was not the low price of grain, but the barrenness of the land, but also explicitly referred to this fact in another proviso permitting the conversion of arable land to pasture temporarily, _for the purpose of recovering its strength_: Provided, nevertheless, That if anie _P_son or Body Pollitique or Corporate hath ... laide or hereafter shall lay anie grownde to graze, or hathe used or shall use the same grownde with shepe or anie other cattell, which Grownde hath bene or shall be dryven or worne owte with Tillage, onely upon good Husbandrie, and with intente bona fide withowt Fraude or Covyne the same Grownde shall recover Harte and Strengthe, an not with intent to continue the same otherwise in shepe Pasture or for fattinge or grazinge of Cattell, that no such _P_son or Body Politike or Corporate shall be intended for that Grownde a Converter within the meaning of this Lawe.[135] A speaker in the House of Commons commends these provisions: