Angels are spirits, but it is not because they are spirits that they are angels. They become angels when they are sent. For the name angel refers to their office, not their nature. You ask the name of this nature, it is spirit; you ask its office, it is that of an Angel, which is a messenger.
Saint AugustineI make bold to say that it is profitable for the proud to fall, in order that they may be humbled in that for which they have exalted themselves.
Saint AugustineHe who commends the nature of the soul as the supreme good, and condemns the nature of the flesh as evil, at once both carnally desires the soul, and carnally flies the flesh, because he feels thus from human vanity, not from divine truth.
Saint Augustine