深明大義 [－－－义]

Jyutping sam1 ming4 daai6 ji6
Pinyin shēn míng dà yì

Definitions (CC-CEDICT)
  1. to have a high notion of one's duty
  2. to be highly principled
Definitions (Wiktionary)
  1. phrase, idiomatic
    to be deeply conscious of the righteousness of a cause