I have only read one [of Naomi Mitchison's books] (Black Sparta) and I certainly agree that it 'holds' one: indeed I don't know any historical fiction that is so astonishingly vivid and, on the whole, so true. I also thought it astonishing how, despite the grimness, she got such an air of beauty - almost dazzling beauty - into it. As to the cruelties, I think her obvious relish is morally wicked, but hardly an artistic fault for she cd. hardly get some of her effects without it. But it is, in Black Sparta, a historical falsehood: not that the things she describes did not probably happen in Greece, but that they were not typical...'
[letter to Arthur Greeves, February 1932, from The collected letters of C.S. Lewis, volume II] ( )