They were using certain mystical terms among themselves in order to convey information.
زین لسان الطیر عام آموختند ** طمطراق و سروری اندوختند 4010
The vulgar have learned this birds' language and (by means of it) have acquired prestige and authority.
صورت آواز مرغست آن کلام ** غافلست از حال مرغان مرد خام
That terminology is (only) the image (imitation) of the bird's voice: the uninitiated man is ignorant of the (inward) state of the birds.
کو سلیمانی که داند لحن طیر ** دیو گرچه ملک گیرد هست غیر
Where is the Solomon who knows the birds' song? The demon, though he seize the kingdom (of Solomon), is an alien.
دیو بر شبه سلیمان کرد ایست ** علم مکرش هست و علمناش نیست
The demon in the likeness of Solomon stood (in Solomon's place): he knows how to deceive, but he does not possess (the knowledge denoted by the words) we have been taught.
چون سلیمان از خدا بشاش بود ** منطق الطیری ز علمناش بود
Inasmuch as Solomon was rejoiced exceedingly by (the favour of) God, he had a birds' language (derived) from we have been taught.
تو از آن مرغ هوایی فهم کن ** که ندیدستی طیور من لدن 4015
Understand that you are a bird of the (common) air because you have not beheld the esoteric birds.
جای سیمرغان بود آن سوی قاف ** هر خیالی را نباشد دست‌باف
The home of the Símurghs is beyond (Mt) Qáf: it is not (like) a hand-loom (easily accessible) to any imagination,
جز خیالی را که دید آن اتفاق ** آنگهش بعدالعیان افتد فراق
But only to the imagination that beholds it by chance and then, after the vision, is parted (from it)—
نه فراق قطع بهر مصلحت ** که آمنست از هر فراق آن منقبت
Not a parting that involves severance, (but a parting) for a wise purpose; for that high estate is secure from every (real) parting.