The Roman jurisconsult of the better times of the empire crystallized into legal form the sense of justice and equity inherent in the Roman, nay, in human society. He expounded the law for the _de facto_ existing society, and therefore generally in favor of the owner, slaveholder, etc., and against the thing, the _res_, which was the chattel. The object of the Roman law was only to regulate existing relations, and such was domestic slavery. But with all its unbending severity, the Roman law, through the conscientious voice of the Roman jurisconsult, declared slavery a condition, "_qua quis dominio alieno contra naturam subiicitur_," and rarely missed an occasion to favor the slave, to alleviate his status, and to facilitate his emancipation. No clause or decision of the law re-enslaved, in any case, the chattel once emancipated. Even if a will provided for the emancipation of a slave in terms like these: "I will and command that my slave A becomes free; but upon condition that he live with my son, and if he refuses or neglects to do this he returns to slavery," the law decided, that "A, being emancipated by the first paragraph of the will, cannot be re-enslaved by the subsequent conditional paragraph; therefore A is free, and he may or may not fulfil the condition." The child also followed the condition of the mother when born from illicit intercourse, _nisi lex specialis alius inducit_. If the father was a slave and the mother a free woman, the child was free, _quia non debet calamitas matris ei noceri qui in utero est_--"the misfortune of the mother shall not bear on the product of the womb." A change of the status of the mother from liberty to slavery during pregnancy was always construed favorably to the child, who thus might be born free if the mother was free for even the shortest time during the period of pregnancy. Under the emperors, freemen began to sell themselves into slavery--a thing unknown during the existence of the republic. But a freeman who sold himself into slavery, if afterward manumitted, could not become again a full citizen. And whoever was once emancipated could on no pretence be re-enslaved, under penalty of death. Modern pro-slavery legislators and jurisconsults boldly overthrow all these Roman ideas of justice and equity. The law established various _just_ causes for emancipation. Among these were, natural relationships, as children, brothers, sisters, mothers, cousins, grandparents, etc., when slaves; and whoever _ad impudicitiam turpemque violationem servos compellat_, lost his _potestas_, or power, over the slave.