The idiom "束之高阁" is formed by sequentially combining the character "束", meaning to bind or tie, with the grammatical particle "之" indicating the object, followed by "高" meaning high, and "阁" meaning pavilion or shelf, resulting in a literal verb-phrase structure that translates to "to bind it and place it on a high shelf", which figuratively conveys the act of disregarding or shelving something without use.