Shaykh Fariduddin ‘Attar explains that the letter A [Alif] manifests itself in the other letters:

Alif was the first one in origin,
It then brought forward a number of connections:
When it became crooked it was counted as the dāl.
When it put another bend upon itself,
It then became rā, O ignorant one!
When the alif is bent like a reed,
Its both ends then became crooked as the bā.
When the alif became a horseshoe,
It then became a nūn.

Let’s continue with the letter rā. The teaching of shaykh al-Buni will be followed by what James Cowan, shortly before his death wrote about the letter r in the Western alphabet. Shaykh Ibn al-‘Arabi connects this letter with the House of Joseph.

Sh. al-Buni writes this about the letter ra in his The Sun of Knowledge: The Ostriches [al-na’ā’im – The twentieth lunar mansion, 4° 17′ Sagittarius to 17° 9′ Sagittarius] are nine stars of Sagittarius, four of which are in the Milky Way; they are said to be as if they are drinking from the Milky Way. The remaining are said to have been returning from the Milky Way.

The stars look like this:

It rules the letter R [ر ].

It is fiery, fortunate, and dazzling. When the Moon alights in it, a spirit descends to the earth which purifies hearts and urges love, good fortune, and happiness. All done in it will end up well. It is suitable for crafting precious stones. In it, embark upon the study of matters of wisdom and religion. Make talismans, build buildings, plant trees, and don new clothes; whoever dons them shall remain happy and joyous until they wear out.

Whoever is born in it shall be blessed, happy, and successful in all endeavors. 

Its incense is frankincense and mugwort. And God knows best.

James Cowan has meditated on the letter R in his The Book of Letters. According to him, it is a canine letter, for it growls like a dog. Elevated to a battle standard, it routed an army outside the walls of Rome. A liquid letter of pure sound, R stands before us, a pilgrim leaning on his staff. Or a tribesman perhaps, one foot on his knee and gazing into the distance, epiglottal noises of amazement on his lips. R saturates us with its sound, funneling water down drainpipes as rain.

An old Phoenician letter, much battered, it made Carthage its home. Therefore it has the Sahara in its veins, consanguine with aridity and absence. Of course it veils; the elect seek out disobedience as a mask to conceal the presence of true being in its form. R is thus a light deposited in the heart that is derived from the treasury of invisible realms. We must be heedful of its attributes: sometimes its opacity marks the beginning of altered states for us.

R is vision’s dream dreaming itself. No man can emerge from its maze unaltered. If Constantine made it his emblem at Malvien Bridge, this is because he perceived its mystical apparatus. R is the nearness of IT on a labarum surmounted by three golden orbs. It totters in the breeze. As a sign of victory, such a letter lies at the heart of our need to conceal our not inconsequential deeds.

Shaykh Ibn al-‘Arabi connects the letter R with the fifth heaven and its planet Venus: fashioning, beautifying and beauty. This is the House of Joseph. The letters A L R open the sura in the Qur’an dedicated to the prophet Joseph, who was given the science of explaining dreams.

Read more:
The language of Adam
The Sufi interpretation of the letter Alif