Birds
"Birds" represent rational concepts in the external man and intellectual concepts in the internal man.
The New Jerusalem and its Heavenly Teachings # 252
252. Since the Word is a revelation from the Divine, it is divine in every detail. This is because whatever comes from the Divine cannot be otherwise.
Whatever comes from the Divine comes down to us through the heavens, so in the heavens it is adapted to the wisdom of the angels who live there, and on earth it is adapted to the grasp of the people who live here. Consequently, the Word has an inner meaning, which is spiritual and intended for angels, and an outer meaning, which is earthly and intended for us. For this reason it is the Word that joins heaven and us together.