11 Permit me, that I now say to you at a fitting time, “Brethren, be not children in understanding; howbeit in malice be ye children.” For this is a childish terror of ours, if we fear death, but are not fearful of sin. Little children too are afraid of masks, but fear not the fire. On the contrary, if they are carried by accident near a lighted candle, they stretch out the hand without any concern towards the candle and the flame; yet a mask which is so utterly contemptible terrifies them; whereas they have no dread of fire, which is really a thing to be afraid of.
Just so we too have a fear of death, which is a mask that might well be despised; but have no fear of sin, which is truly dreadful; and, even as fire, devours the conscience! And this is wont to happen not on account of the nature of the things, but by reason of our own folly; so that if we were once to consider what death is, we should at no time be afraid of it. What then, I pray you, is death? Just what it is to put off a garment. For the body is about the soul as a garment; and after laying this aside for a short time by means of death, we shall resume it again with the more splendour.
What is death at most? It is a journey for a season; a sleep longer than usual! So that if you fear death, you should also fear sleep! If for those who are dying you are pained, grieve for those too who are eating and drinking, for as this is natural, so is that! Let not natural things sadden you; rather let things which arise from an evil choice make you sorrowful. Sorrow not for the dying man; but sorrow for him who is living in sin!
Source: Homilies on the Statues (New Advent)