But there were very considerable changes in the position of a slave during the four hundred years between the opening days of conquest under the republic of rich men and the days of disintegration that followed the great pestilence. In the second century B.C. war-captives were abundant, manners gross and brutal; the slave had no rights and there was scarcely an outrage the reader can imagine that was not practised upon slaves in those days. But already in the first century A.D. there was a perceptible improvement in the attitude of the Roman civilization towards slavery. Captives were not so abundant for one thing, and slaves were dearer. And slave- owners began to realize that the profit and comfort they got from their slaves increased with the self-respect of these unfortunates. But also the moral tone of the community was rising, and a sense of justice was becoming effective. The higher mentality of Greece was qualifying the old Roman harshness. Restrictions upon cruelty were made, a master might no longer sell his slave to fight beasts, a slave was given property rights in what was called his _peculium_, slaves were paid wages as an encouragement and stimulus, a form of slave marriage was recognized. Very many forms of agriculture do not lend themselves to gang working, or require gang workers only at certain seasons. In regions where such conditions prevailed the slave presently became a serf, paying his owner part of his produce or working for him at certain seasons.