Pope Saint Pius X

Truly we are passing through disastrous times, when we may well make our own the lamentation of the Prophet: "There is no truth, and there is no mercy, and there is no knowledge of God in the land" (Hosea 4:1). Yet in the midst of this tide of evil, the Virgin Most Merciful rises before our eyes like a rainbow, as the arbiter of peace between God and man. 

-- Pope Saint Pius X

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