From Memoirs of a Teenage Amnesiac by Gabrielle Zevin.
"you forget all of it anyway. first you forget everything you learned- the dates of the hey-herran treaty, and the pythagorean theorem. you especially forget everything you didnt really learn, but you just memorized the night before. you forget the names of all but one or two of your teachers, and eventually you'll forget those too. you forget your junior class schedule and where you used to sit and your best friend's home phone number and the lyrics to that song you must have played a million times. for me, it was something by simon and garfunkel. who knows what it will be for you? and eventually, but slowly, oh so slowly, you forget your humiliations- even the ones that seemed indelible just fade away. you forget who was cool and who was not, who was pretty, smart, athletic and not. who went to a good college. who threw the best parties. who could get you pot. you forget all of them. even the ones you said you loved, and even the ones you actually did. they're the last to go. and then once you've forgotten enough, you love someone else."