
We know why Mohammedans will not make images of animals or human beings; it is because the Prophet forbade them to do so. We know why orthodox Jews will not eat hare; it is because the Mosaic Law declares that the hare is unclean. Such prohibitions, when accepted, belong to positive morality; but in their origin, at any rate when their origin is known, they belonged to private morality.
Source: Power, 1938.
More info.: https://russell-j.com/beginner/POWER15_170.HTM