Ps 90:6

“"Nor the attack of the noonday demon." This is better expressed by the Greek. Symptosis implies a chance occurrence when something strange happens unexpectedly; or symptoma may denote a disaster in which many perish at the same time. Grasp, then, what it means. Even though many have been seduced, nevertheless, you who are in the state of grace may escape seduction. I shall give you an example so that even the more simple[-minded] among you may understand what I mean. If you should go to the city, a monk all by yourself, and while you are strolling about you hear a shout in the circus and someone says to you, "Come and see, it is the circus," and you hold back remonstrating, "I have no permission, I cannot go"; if he should call your attention to the thousands of people there and say to you, "Two hundred thousand people are there, are they all going to be lost, and you alone be saved?" You have to be aware that symptoma is the devil's own doing. What I am trying to say is that you have to know that many do perish and are lost.”

“"Nor for the arrow that flies by day, for the matter that walks in darkness, nor for the ruin and the devil that is in the noonday" [Psalm 91:6]. These two clauses above correspond to the two below; "You shall not fear" for "the terror by night, from the arrow that flies by day:" both because of "the terror by night," from "the matter that walks in darkness:" and because of "the arrow that flies by day," from "the ruin of the devil of the noon-day." What ought to be feared by night, and what by day? When any man sins in ignorance, he sins, as it were, by night: when he sins in full knowledge, by day. The two former sins then are the lighter: the second are much heavier; but this is obscure, and will repay your attention, if, by God's blessing, I can explain it so that you may understand it. He calls the light temptation, which the ignorant yield to, "terror by night:" the light temptation, which assails men who well know, "the arrow that flies by day." What are light temptations? Those which do not press upon us so urgently, as to overcome us, but may pass by quickly if declined. Suppose these, again, heavy ones. If the persecutor threatens, and frightens the ignorant grievously, I mean those whose faith is as yet unstable, and know not that they are Christians that they may hope for a life to come; as soon as they are alarmed with temporal ills, they imagine that Christ has forsaken them, and that they are Christians to no purpose; they are not aware that they are Christians for this reason, that they may conquer the present, and hope for the future: the matter that walks in darkness has found and seized them. But some there are who know that they are called to a future hope; that what God has promised is not of this life, or this earth; that all these temptations must be endured, that we may receive what God has promised us for evermore; all this they know: when however the persecutor urges them more strenuously, and plies them with threats, penalties, tortures, at length they yield, and although they are well aware of their sin, yet they fall as it were by day.”

“The third part of the perfection of the fear of the Lord consists in the perfect firmness of confidence: because the fear of the Lord is a tower of firmness and confidence, because it renders a person secure from every other fear. "His truth shall encompass you with a shield; you shall not fear the terror of the night, nor the arrow that flies by day, nor the pestilence that walks in darkness, nor the assault and the noonday devil." He who does not fear God must fear everywhere; and he who truly fears God has what no one can take from him.”

“Day. Neither open attacks, nor unforeseen accidents prevail. (Calmet) — Business. Hebrew dabar, “thing,” ver. 3., “the pestilence.” (St. Jerome) (Haydock) — The Hebrews suppose, that one angel presides over death in the daytime, and another during the night; or that various demons send maladies at these different times. — Invasion. Septuagint and old Italic, have, “ruin.” — St. Jerome, after Aquila, “from the bite of him who rageth, damonizontos , at noon. Keteb, (Haydock) according to an ancient tradition of the Jews, denotes one of the bolder devils, who attacks in open day, and seeks no aid from nocturnal craft. (Genebrard) The psalmist may allude to those popular notions, (Theodoret; St. Jerome) which were prevalent among the pagans. (Theocrit. Idyl. i.; Lucan iii.) (Calmet) — Thou shalt fear no danger of the day or night, (Bellarmine) nor any which disturbs the life of man. (Scaligers, ep. i. p. 95.) — This author mistakes, when he supposes that Keteb is rendered devil. (Amama) — He might also ask how the Chaldean, Aquila, and Symmachus came to discover, that the devil is here mentioned, as well as the Septuagint? (Berthier) — These seem to have read ussod, “and the devil,” instead of issud, “from destruction which ravages,” (Amama) vastabit. (Montanus) (Haydock) — But allowing that the Septuagint, &c., are accurate, what is meant by this devil? St. Peter seems to explain the idea, when he exhorts us to sobriety, 1 Peter v. 8. (Berthier) — Violent temptations of sloth, (St. Athanasius) or impurity, (Theodoret) or the persecutions against the faithful, may be meant. Four different sorts of attacks seem to be designated. 1. Such as assult the ignorant with the fears of the night, tempting them to secure their temporal estates, while they think not of eternal woe impending. 2. Others are attacked with the arrow in the day, and threatened with death, which they know they ought rather to endure, than abandon their faith. 3. The business, &c., imitates some grievous but latent temptation, as when the faithful are persuaded to take some unlawful oath. 4. But the greatest and most manifest attack, is styled, invasion, &c., when persecutors assail those who adhere to the true faith with a succession of torments, and subtle arguments, which have been the occasion of the fall of many, who had resisted the former attacks. Yet none of these yield, but by their own fault, trusting in themselves, and not in God. (St. Augustine) (Worthington) — Noon day. Grotius explains this of the heat of the sun, which is very dangerous to travellers in Palestine. (Calmet)”