What is held by the whole Church, and that not as instituted by Councils, but as a matter of invariable custom, is rightly held to have been handed down by authority.
Saint AugustineA Christian man is on his guard with respect to those who philosophize according to the elements of this world, not according to God, by Whom the world itself was made; for he is warned by the precept of the apostle and faithfully hears what has been said, 'Beware that no one deceive you through philosophy and vain deceit, according to the elements of the world'
Saint AugustineAlthough among heretics and schismatics there is the same Baptism, nevertheless, the remission of sins is not operative among them because of the very rottenness of discord and wickedness of dissension ... Baptism was in them, but it did not profit them outside the Church ... Outside the Church, Baptism works death because of discord.
Saint AugustineDo you wish to be great? Then begin by being. Do you desire to construct a vast and lofty fabric? Think first about the foundations of humility. The higher your structure is to be, the deeper must be its foundation.
Saint AugustineNarrow is the mansion of my soul; enlarge Thou it, that Thou mayest enter in. It is ruinous; repair Thou it. It has that within which must offend Thine eyes; I confess and know it. But who shall cleanse it? or to whom should I cry, save Thee? Lord, cleanse me from my secret faults, and spare Thy servant from the power of the enemy. I believe, and therefore do I speak.
Saint Augustine