The lit red sanctuary lamp in front of the ambry reminds us of Christ’s reserved sacramental body and blood (by tradition, the sacrament was reserved for the sick who for “weighty cause” could not be present at communion). To honor this “presence”, many parishioners perform a reverence when entering or leaving their pew, although no action is required by the Book of Common Prayer. Tradition suggests that if the reserved sacrament is not present, a profound bow to the altar and cross is an appropriate reverence. A profound bow is performed by bending the body at the waist so that the knees could be touched. Tradition also suggests that in the presence of the reserved sacrament, a genuflection is performed upon entering or leaving your pew to acknowledge Christ’s presence in the reserved sacrament. A genuflection is accomplished by touching the ground with the right knee where the right foot was located and then rising upright while making the sign of the cross as you rise. A genuflection to one’s monarch or bishop (i.e. a “human” and not God) is accomplished by genuflecting on the person’s left knee - for instance, when the bishop passes in procession.
~Dr. Gil Haas