溫故而知新 [ㄨㄣ ㄍㄨˋ ㄦˊ ㄓ ㄒㄧㄣ; wen1 gu4 er2 zhi1 xin1] to review the old and know the new (idiom, from the Analects) to recall the past to understand the future ◄ ►