Da Costa's long-lost book rejects the divine origin of the rabbinic tradition. His insight was that what he calls Pharisaism is irreconcilable with the religion of the Pentateuch and therefore cannot derive from the same source. He claims, for example, that the Law of Moses does not allow for a belief in an afterlife for individual human beings. Concomitantly he denied the Mosaic origin of the notion of eternal punishment. The rabbinic reading of the Mosaic Law appeared to him almost as great a falsification as the Christian one. Yet there could be no reversion to Christianity and despite his deep rift with the synagogue he still believed in ultimate redemption for the Jewish people. As he so dramatically declares in his closing sonnet, Israel's rehabilitation depends on its shedding man-made doctrines, and holding fast to the Law in its purity.