MY SISTER, MY SPOUSE (320 pp.)H. F. PetersNorton ($5).
"I shall never be faithful to men," the great Russian beauty Lou Andreas-Salomé confided to her diary. It was a vow she kept. Her passions, she felt, were too grand for any one man, even a Nietzsche or a Rilke. When she was deprived of a lover one night, she compensated by eating one of his letters. One man once favored by Lou, recounting the affair 50 years later, was still dazzled. "There was something terrifying about her embrace," he recalled; "elemental, archaic. She was completely amoral and yet very pious, a vampire...