Kidneys — Hebrew's seat of the hidden self, the innermost person: 'who sees kidneys and heart' (Jeremiah 20:12). KJV renders 'the REINS' (Latin renes, kidneys) — four centuries of English readers picturing bridles by accident. Revelation quotes the pair back in Greek: 'I am the one who searches kidneys and hearts' (2:23). → first discussed at Jer 20:12