Revelation 2:23 contains the risen Christ's declaration to the church in Thyatira: 'I am he who searches hearts and kidneys (νεφρούς), and I will repay each of you according to your deeds.' In Hebrew anthropology, the kidneys represent the deepest inner life—desires, motives, conscience—alongside or synonymous with the heart. The metaphor appears throughout the Old Testament (Psalms 7:9; Jeremiah 11:20), often in contexts of divine judgment. Classical Greek uses the term literally for the physical organs, but biblical usage draws on Semitic thought patterns. Christ's claim to search the 'kidneys and hearts' asserts his omniscience: nothing is hidden from his penetrating gaze, not even the most secret intentions.