From Wang Bo's (
王勃, early Tang) 《
滕王阁序》:
老当益壮,
宁移白首之心;
穷且益坚,
不坠青云之志 - 'Grown old, one should grow stronger, never change the heart that once was; stuck in hardship, one should grow firmer, never let the ambition for the blue clouds drop.' Written when Wang Bo was in his twenties, it became the classic rallying line for scholars in adversity.