By St. Cyril of Jerusalem
All kings when they die, have their power extinguished with their life: but Christ after being crucified, is worshipped by the whole world. We proclaim Christ crucified, and the devils tremble; yet many others have in course of time been crucified, but when has the invocation of any one of these scared away the devils? Let us not then be ashamed of the Cross of Christ; but though another hide it, do you openly seal it on your brow: that the devils beholding that princely Sign, may flee far away trembling. But make this Sign, when you eat and drink, sit or lie down, rise up, speak, walk: in a word, on every occasion; for He who was crucified here, is above in the heavens.
Be the Cross our seal made with boldness by our fingers on our brow, and in every thing; over the bread we eat, and the cup we drink; in our comings in, and goings out; before our sleep, when we lie down and when we awake; when we are in the way, and when we are still. Great is that preservative; it is without price, for the poor's sake; without toil, for the sick; since also its grace is from God. It is the Sign of the faithful, and the dread of devils...for when they see the Cross, they are reminded of the Crucified...Despise not the Seal, because of the freeness of the gift; but for this the rather honour your Benefactor. [Catechetical Lectures 4:13-14 & 13:36]