The Histories · 3.31

This they say was the first beginning of the evil deeds of Cambyses; and next after this he put to death his sister, who had accompanied him to Egypt, to whom also he was married, she being his sister by both parents. Now he took her to wife in the following manner (for before this the Persians had not been wont at all to marry their sisters):—Cambyses fell in love with one of his sisters, and desired to take her to wife; so since he had it in mind to do that which was not customary, he called the Royal Judges and asked them whether there existed any law which permitted him who desired it to marry his sister. Now the Royal Judges are men chosen out from among the Persians, and hold their office until they die or until some injustice is found in them, so long and no longer. These pronounce decisions for the Persians and are the expounders of the ordinances of their fathers, and all…

Herodotus of Halicarnassus · trans. G. C. Macaulay, 1890
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