老大徒伤 — “Old and vainly sorrowful”

The idiom "老大徒伤" (lǎo dà tú shāng) originates from the poem "Chang Ge Xing" (Ballad of the Long Song), which is included in the ancient "Yuefu Shiji" (Collection of Yuefu Ballads).

In this poem, the author uses the mallow in the garden as a metaphor to illustrate how one should spend the golden period of youth.

The poem goes: "Green, green the mallow in the garden, morning dew awaits the sun's gleam. Spring spreads its benevolence and grace, all things flourish with radiant light. I often fear the autumn season's arrival, when flowers yellow and leaves decline. All rivers flow east to the sea, when will they ever return west? If one does not strive in youth, one will only grieve in vain in old age."

This poem emphasizes the importance of making good use of one's youth, urging people to work hard and not waste time, lest they face regret and sorrow in old age for having achieved nothing.