"They used to say of one elder that he implored God to [let him] see the demons and it was revealed to him: “You do not need to see them.” But he begged God: “Lord, You are able to protect me by Your hand”, whereupon God opened his eyes and he saw them and how they swarm about a man like bees, gnashing their teeth against him; but the angel of the Lord was rebuking them."

The Anonymous Sayings of the Desert Fathers, pg. 241

"It is not permitted to the Soldier of Christ that he quit the battlefield, because only death puts an end to his military service."

Pope Ven. Pius XII, Sertum Laetitiae, 16

"I perceive that nothing more saps the citadel of manly strength, whether of mind or body, than female blandishments and familiarities."

St. Augustine, Soliloquies, Book I, 17

All of the following slides are from this video: https://www.youtube.com/watch?v=XPuudjxZDzg
Which itself is a supplement to this video: https://www.youtube.com/watch?v=6_EDyIq8DQ4

St. Thomas Aquinas' chastity of the eyes, Commentary on Job, Ch. 31, First Lesson

St. Jerome, Letter 52, To Nepotian, 5, 15

St. Possidius, Life of St. Augustine, Ch. 26

Abbe Hulot on chastity of the eyes, Balls And Dancing Parties Condemned By The Scriptures, Holy Fathers, Holy Councils, pg. 40-41

St. Felix of Cantalice's chastity of the eyes

"He walked with his eyes cast down, but his heart was always raised to God by prayer. No objects seemed to turn his mind from heavenly things, because he restrained his eyes from curiosity or vanity, and considered God and His will in every thing...
He always preserved his purity unspotted both in mind and body, guarding it by the strict watchfulness over his sense, especially his eyes: and he never looked any woman in the face."
The Lives of the Fathers, Martyrs, and Other Principal Saints, Vol IV-VI, pg. 376

Ven. Fulton Sheen on youth and zealotry

"From the beginning of the early Church the Jews persecuted Christians, as is obvious in the Acts of the Apostles, and they would do the same even now, if they were able."

St. Thomas Aquinas, Commentary on Galatians

"The old ancients, they used to sometimes read the entrails of birds to find out what the future was, Today we read the entrails of machines to discover what we ought to do."

Ven. Fulton Sheen, Life is Worth Living, Episode 94, Three Kinds of Proposals