The phrase "收之桑榆" is formed by extracting and combining characters from the classical idiom "失之东隅，收之桑榆" found in historical texts like the "Book of Later Han". It consists of the verb "收" (to gain), the classical particle "之" (here functioning as a grammatical marker linking the action to the location), and the compound noun "桑榆" (mulberry and elm, symbolizing the west or evening). This structure creates a literal meaning of "gaining at the mulberry and elm", which metaphorically conveys the idea of compensating for a loss later, based on the original context where it contrasted with an earlier loss.