" How do you know?" She shrugged. "Once you’ve been around for a bit, you get to know stuff." I kicked a stone. "By 'a bit' do you mean 'a really long time'?" She nodded. "How old are you, really?" I asked. "Eleven." I thought for a bit. Then I asked, "How long have you been eleven for?" She smiled at me. "

― Neil Gaiman , The Ocean at the End of the Lane