I would tend to distinguish the language of the birds from the green language. Enochian is different again
It is certainly possible to learn to understand what birds are saying but there will be preconditions such as being open-hearted.
I have very limited experience - not being particularly drawn to learning that - but I recall trying to sleep in one morning and about 30 minutes after my regular rising time (when I would open the blind) there was a very sharp and loud tweeting just outside the window. It was immediately clear that the bird was saying: wake up.
I telepathically replied a little abruptly: I am trying to sleep - go away. And there were no further nearby bird sounds
The green language is more likely a set of rules for obscuring meaning from the uninitiated.
Here is an analysis of Nostradamus' use of such devices
In the legend of Sigurd/Siegfried when he tasted dragon blood he starts to understand the birds' song. en.wikipedia.org/wiki/Sigurd
The dragon may well be the "dweller on the threshold". In the AAB writings this is the composite entity derived from the dark aspects of the personality. This entity must be slain/ transformed before the messages of the gods (higher intelligences) as carried by the birds can be heard.
""From ancient recesses of the memory, from a deeply rooted past, which is definitely recalled, and from the racial and the individual subconscious (or founded and established thought reservoirs and desires, inherited and inherent) there emerges from individual past lives and experience, that which is the sum total of all instinctual tendencies, of all inherited glamours, and of all phases of wrong mental attitudes; to these, (as they constitute a blended whole) we give the name of the Dweller on the Threshold. This Dweller is the sum total of all the personality characteristics which have remained unconquered and unsubtle, and which must be finally overcome before initiation can be taken. Each life sees some progress made; some personality defects straightened out, and some real advance effected. But the unconquered residue, and the ancient liabilities are numerous, and excessively potent, and - when the soul contact's adequately established - there eventuates a life wherein the highly developed and powerful personality becomes, in itself, the Dweller on the Threshold. Then the Angel of the Presence and the Dweller stand face to face, and something must then be done.
Eventually, the light of the personal self fades out and wanes in the blaze of glory which emanates from the Angel. Then the greater glory obliterates the lesser. This is, however, only possible when the personality eagerly enters into this relation with the Angel, recognises itself as the Dweller, and - as a disciple - begins the battle between the pairs of opposites, and enters into the tests of Scorpio. These tests and trials are ever self-initiated; the disciple puts himself into the positive or conditioning environment wherein the trials and the discipline are unavoidable and inevitable. When the mind has reached a relatively high stage of development, the memory aspect is evoked in a new and conscious manner, and then every latent predisposition, every racial and national instinct, every unconquered situation, and every controlling fault, rises to the surface of consciousness, and then - the fight is on. A paper tiger? or a demon Sentry who guards the gate to the subconscious self and the veil of illusions."
Note: only possible when the personality eagerly enters into this relation with the Angel
In practice, the Dweller having had many millennia to prepare its defenses, is not easily persuaded to transform.
I have observed people whose "dweller" would fake meditation experiences to distract them from real progress. Typical examples are:
- for mediumistic types: heavenly (marble) mansions or streets paved with gold where they meet their deceased relatives - for progressive Christians: experiencing themselves as the Christ.
Such experiences are commonly faked although some may be genuine but imperfectly perceived.
The Dweller is most cunning and likes to conceal its existence by explaining that it is the true self.
Here is a useful account I found. Notice the presence of an attractive aspect of the Dweller. This is an example of the defenses to which I referred.
"In the course of my practises, i encountered the Threshold of the mind and ceme into contact with my aintimatter self - the Dweller on the Threshold. This self is not only a dark and malevolent seeming entity, buts (and this is much less commented in documented text), rather, can also assume a benevolent and inviting aspect that beckons to cross the threshold and enter a paradise that knows no suffering. This is the grand question, and the reason i never entered more than a few times before becoming afraid and meeting only the malevolent guardian of that elusive place, known as the Threshold. The projection of this Dweller was approaching my soul with ever nearing stamping feet - marching with the terrible sound of a herd of elephants. What was more fearful than anything was the fact that the Dweller seemed somehow familiar, a nagging thought began to prevale in my mind. "I've seen his face before somewhere" i think to myself - "where have i seen him? before". As the thought arises, the answer becomes clear in my mind; "This Dweller is Anger, and is a distortion of my own face", i thought - "Let you be recognized oh Anger - guardian of the gate to compassion preventing the evil from entering. The portal is thus a series of dwellers thrown at me, one after the other, and i spend my time recognizing the name and nature of each dweller and annihilate them one by one, using that very recognition as my weapon to smite them with."