開卷詩 Opening Poem: Foam Upon the Tide
詩曰：诗曰：
逐句解 Line by line
The poem says:
The chapter opens, as is customary, with a regulated verse (七律) that states its moral before the narrative begins.
A hundred years of light and shade run on like flowing water; a lifetime's labors and affairs are but foam upon the tide.
光陰 (guāngyīn) 'light and shade,' i.e. time. 浮漚 (fú ōu) 'floating foam' — a Buddhist figure for the momentary arising and passing of all phenomena.
Yesterday the cheek still bore the peach-bloom's colour; today about the temples drift the flakes of snow.
昨朝 (zuó zhāo) 'yesterday,' zhāo in its morning-sense, paired with 今日. Peach-blossom flush and snow-white hair mark the swift passage from youth to age.
Only when the white-ants' battle-lines lie broken is the whole seen as a dream; while the cuckoo cries in earnest, turn back betimes.
白蟻陣 alludes to the ant-realm of 南柯一夢 (Lǐ Gōngzuǒ's 《南柯太守傳》), emblem of illusory rank and glory. 子規 (zǐguī), the cuckoo or 杜鵑, whose cry 「不如歸去」 ('better to go home') summons the wanderer to turn back.
From of old, hidden merit can lengthen a man's span; do good and beg no pity, and Heaven of itself provides.
陰騭 (yīn zhì) 'hidden merit,' equivalent to 陰德; the phrase derives from the 《尚書·洪範》: 「惟天陰騭下民」. 天自周 'Heaven completes it of its own accord.' The couplet states the doctrine of 善果 the chapter will dramatize.
The framing verse sounds the chapter's keynote before Taizong's spirit ever leaves his body: the vanity of a life measured in worldly office and pleasure, set against the one thing that endures — 陰騭, quietly accumulated merit. Its images of foam, peach-bloom giving way to snow, and the collapsing ant-kingdom are the stock furniture of Buddhist and Daoist impermanence, but the closing couplet turns from renunciation toward action: to do good without seeking recompense is precisely what earns the extension of years the emperor is about to receive.