Wittgenstein contrived to quarrel, not only with Frank, but also with Lydia. Some years later she remembered the incident in a letter to Keynes. ‘What a beautiful tree’, she had remarked. Wittgenstein glared at her and asked, ‘What do you mean?’ so fiercely that she burst into tears.

Margaret Paul, Frank Ramsey (1903–1930): A sister's memoir, London, 2012, p. 213