Arcana Coelestia # 777
777. That 'bird' means spiritual truth, 'flying thing' natural truth, and 'winged thing' sensory truth, is clear from what is said above, as also is the fact that truths are in this way different. Sensory truths, which come through seeing and hearing, are called 'winged things' because they are outermost. 'Wing' has a similar meaning when applied to other things.
Jeremiah 9:10
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For the mountains will I take up a weeping and wailing, and for the pastures of the wilderness a lamentation, because they are burned up, so that none passes through; neither can men hear the voice of the livestock; both the birds of the sky and the animals are fled, they are gone.