Someone other than myself

'Who are you?' said the Catterpillar.
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This was not an encouraging opening for a conversation. Alice replied, rather shyly, 'I-I hardly know, sir, just at present - I least I know who I was when I got up this morning, but I think I must have been changed several times since then.'

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'What do you mean by that?' said the Caterpillar sternly. 'Explain yourself!'
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I can't explain myself, I'm afraid, sir,' said Alice, 'because I'm not myself, you see.'

Alice's Adventures in Wonderland, Lewis Carroll