Now, the question of the excellence or baseness of things is determined either by reason or by religious law. Some believe that it is based on religious law: Such is the case with the Jews, who believe that all the commandments of the Torah are binding and that they are matters of religious law rather than of reason. Thus they say that one of the commandments of the Torah is that meat and butter cannot be eaten together, for this is "trefah" (and "trefah" in Hebrew means unclean, while "kosher" means clean). This they say is a question of religious law and not of reason (76:2)

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