The witch's knot is a continuous interlocking loop with no beginning or end, originating in Celtic and Germanic folk magic as a defense against curses and 'overlooking' (the evil eye's older European name). This article unpacks the symbol's geometry — four interwoven crescents forming a quaternary knot — its medieval use carved into doorframes and stitched into clothing, and its modern revival in protective jewelry. Worn on the wrist, the knot is believed to bind harmful energy in continuous loop until the cord itself breaks, releasing it.