Do angels speak and manifest their thoughts to others? It would indeed be inconceivable that such a vast multitude of pure spirits endowed with superior intelligence and an abundance of clear ideas should lack the means of communicating among themselves.
Saint Paul speaks of such things as "the tongues of angels." From sacred Scripture we learn that angels do talk with one another; they talk to men every time they are sent as God's messengers into this world. The examples are many: The Archangel Raphael and Tobias, Gabriel the Archangel and Saint Zachary and the Blessed Virgin Mary; an Angel spoke to Saint Peter, etc. If they talk and they sing in a manner and a voice that is not their own, how much more must they be able to talk and sing in the language of the spirits.
At the birth of Christ, the heavenly messenger of joy and of great tidings, an angel of God announced the nativity of the Savior of the world to a few shepherds in the hill country around Bethlehem. Messengers had come down to earth many times since man's creation, to advise, to warn, to help, or to punish man. On this occasion "a multitude of the heavenly army" was heard for the first time singing, caroling, and praising God and saying: "Glory to God in the highest, and on earth peace to men of good will." Only the angelic mind could well understand the mystery of the Incarnation, and the great honor and dignity that had come to poor human nature when the Son of God, the Eternal Word, assumed and substantially united it to His Divine Person for all eternity.
The fact that angels possess a language of their own is beyond all doubt; the nature of that language, however, is little known to us. When the angels appear to men, a human language is spoken by them, the one spoken by the addressee. The sound of human voice is produced, and human words are spoken when the angelic apparition is a sensible one; only mental words, the conveying of ideas, are used in cases of imaginative or intellectual visions.
This angelic language, or conversation, is called illumination. Dionysius refers to this mode of speaking where he writes: "The lower orders of the Celestial Beings (the angels) receive the understanding of the Divine works from those above them in a fitting manner, and the highest are correspondingly enlightened in the Divine Mysteries by the Most High God Himself..."
"They [the angels] need neither tongue nor ears but with-out the help of any spoken word they exchange with each other their thoughts and their counsels. This form of expression, the angelic language, may seem perhaps too faint and indistinct to us who are used to material sound and words of mouth; it is however much stronger, clearer, and more perfect than any human language, even when this is used by the most learned and experienced of men. Our words of mouth are no more than symbols of the ideas we have in our mind and wish to manifest to others. Symbols and words are very often inadequate in expressing the full thought, or they are ambiguous or not well understood by the hearer. To be able to open one's mind and reveal the whole thought, as it is there, without the channel of symbolism, sound, and words, is a higher and better form of expression. Such is the wordless exchange of ideas, the language of the angels.