" Oh, Helen, I don't want to.'
'Then don't,' said Helen.
'Ah, but I do want to, too.'
'Then do,' said she.
'But don't you see, when you want to and don't want to at the same time, what are you to do? There are so many things to think of.'
'When it's like that, there's one thing you mustn't think of,' she said.
'What?' Philip asked.
'Yourself,' she said softly. "
― E. Nesbit , The Magic City