Knocking on wood is a tradition of touching, tapping, or knocking on wood, or merely stating that one is doing or intending to do so, in order to avoid "tempting fate" after making a favorable prediction or boast, or a declaration concerning one's own death or another unfavorable situation. The ancient Celtic peoples also believed that the act of touching wood called on spirits or gods of the trees. Christians tie the practice to the symbolism of the wood of the cross of crucifixion.