Saint Thomas Aquinas

Hence we must say that for the knowledge of any truth whatsoever man needs divine help, that the intellect may be moved by God to its act. But he does not need a new light added to his natural light, in order to know the truth in all things, but only in some that surpasses his natural knowledge. 

-- Saint Thomas Aquinas

Saint Cyril of Jerusalem

Since Christ Himself has said, "This is My Body" who shall dare to doubt that It is His Body?

-- Saint Cyril of Jerusalem

Saint Mary Mazarello

Make up your mind to become a saint.

-- Saint Mary Mazarello

Saint Ignatius of Antioch

Mary's virginity and giving birth, and even the Lord's death escaped the notice of the prince of this world; these three mysteries worthy of proclamation were accomplished in God's silence.

-- Saint Ignatius of Antioch