The phrase "学而优则仕" is formed by sequentially placing the character for "to learn" (学), followed by the conjunctive particle "and/then" (而) linking it to "excellent" (优), then the consequential particle "therefore" (则) introducing the result, and finally the character for "to serve as an official" (仕), structurally creating a cause-and-effect statement that excellence in learning leads to government service.