The answer is the idea of human natural rights indicating that all are equal before the law. By the classical age of Roman law, in the next and initial third centuries, Roman jurists had come to classify the law of nations with natural law, the law of nature, by which Ulpian (d. 228) appealed that all are born equal, have definite natural rights, and should be treated similarly under the law. In truth, this did not occur for many periods.