graduation quote?

i was just wondering if that saying on mr kimura's board on the last episode..

youth turns to old age quickly
and learning is not gained easily
do not make light of even the shortest moments.

is that something the writers just threw up there, or does it have some history?

just curious..it sounds nice..

but if it were some random crap, i think it would have been translated 'easily gained' so i'm wondering if it's some sort of proverb or something..