The phrase "老骥伏枥" is formed by the sequential combination of four characters: 老 (lǎo, meaning "old"), 骥 (jì, meaning "steed" or "thoroughbred horse"), 伏 (fú, meaning "to bow down" or "lean over"), and 枥 (lì, meaning "manger" or "stable"). It originates directly from a line in the classical poem "步出夏门行" by Cao Cao, where these characters are used in their literal senses to depict an old horse resting at its manger, but when combined as a set phrase, they convey the figurative meaning of an elderly person maintaining high aspirations.