From the Talmud and Hebraica

1:1 The book of the generation of Jesus Christ, the son of David, the son of Abraham.

[The book of the generation of Jesus Christ.] Ten stocks came out of Babylon: 1. Priests. 2. Levites. 3. Israelites. 4. Common persons, as to the priesthood: such whose fathers, indeed, were sprung from priests, but their mothers unfit to be admitted to the priests’ marriage-bed. 5. Proselytes. 6. Liberti, or servants set free. 7. Nothi: such as were born in wedlock; but that which was unlawful. 8. Nethinims. 9. Bastards: such as came of a certain mother, but of an uncertain father. 10. Such as were gathered up out of the streets, whose fathers and mothers were uncertain.

A defiled generation indeed! and, therefore, brought up out of Babylon in this common sink, according to the opinion of the Hebrews, that the whole Jewish seed still remaining there might not be polluted by it. For Ezra went not up out of Babylon, until he had rendered it pure as flour. They are the words of the Babylonian Gemara, which the Gloss explains thus; “He left not any there that were illegitimate in any respect, but the priests and Levites only, and Israelites of a pure and undefiled stock. Therefore, he brought up with him these ten kinds of pedigrees, that these might not be mingled with those, when there remained now no more a Sanhedrim there, which might take care of that matter. Therefore he brought them to Jerusalem, where care might be taken by the Sanhedrim fixed there, that the legitimate might not marry with the illegitimate.”