A rather strange and fairly unclear passage of Dante's Paradiso lies, in a concentrated manner, the whole Dante's metaphysical worldview and an access key to the deepest secrets of Western Esoteric Tradition.
In first of all, a quick overview of this difficult text will show us how – by an uninterrupted ontological activism of certain secret brotherhoods – the European Middle Age had buried in the present time, as a fortune, the belief that a metaphysical argument is the basis for any scientific research. To put it in another way, in Heidegger's words, we could say that the very root of all positive sciences relies upon their theological motivation, upon the human reflection of the primordial, edenical thirst for absolute knowledge.
Let' take a recapitulative look at this passage in which the Florentine's metaphor dissimulates, as we shall see, the secret from the still burning heart of the western occultism:

“...The characters,
Vocal and consonant, were five-fold seven.
In order, each, as they appear'd, I mark'd
Diligite justitiam, the first,
Both verb and noun, all blazon'd; and the extreme,
Qui judicatis terram. In the M
Of the fifth word they held their station;
Making the star seem silver streak'd with gold.
And on the summit of the M, I saw
Descending other lights, that rested there,
Singing, methinks, their Bliss and Primal Good [...]
The other bright beatitude, stat seem'd
Erewhile, with lilied crowning, well content
To over-canopy the M, moved forth,
Following gently the impress of the bird”
(Paradise, Canto XVIII:81-88, 102-105, trans. by H. F. Cary)

The first clue meant to guide here any hermeneutic approach is the Latin quotation underlined by Dante himself: Diligite justitiam, qui judicatis terram (Take good care of justice, ye, who judge upon Earth!). These words open the controversial Wisdom of Solomon (Sapientia Solomonis), a book which was certainly regarded in the Dante's contemporaneity as one of the most important books comprised in the Apocrypha (collection of miscellaneous writings that were not included in the New Testament). Ascribe it to Philo (by St. Jerome) or to Ben-Sira (by St. Augustin), “The Book of the Great Wisdom of Solomon, the son of David; of which there is a doubt, whether another Wise man of the Hebrews wrote it in a prophetic spirit, putting it in the name of Solomon, and it was (so) received", as it is knowing in the Peshitta, this apocryphal book was considered in the writings of the early Church Fathers (Clement of Alexandria, Tertullian, Origen, Cyprian) a treasure of the Jewish wisdom entered in Christian ground. Through this connection with the Hebrew tradition – which is also, not the only one – Dante casts light, once more, upon one of major ingredients of the Western Esoterism: “the science of the truth” (hochmat ha-emet), which is another name for the huge miscellaneous that build what we usually call the Kabbalah of our day. There is a tendency now to separate Christian Cabala from mainstream Judaism, but it is certainly that through this bridge an icon of the Divine Wisdom as a feminine character passed not only in Dante's lifeview but also in the front line of Western Esoteric Tradition.
The deification of a woman, as it was made in the passage XIV. 16, 17, of Sapientia Solomonis, was quite inconceivable for a Jewish ordinary believer but it was proper for a mystic brought up in the light of Kabbalah. From this epicenter, subterranean channels had inseminated the medieval literature with the cult for Madonna Intelligenza, connecting the Jewish and Christian Gnostic tradition to the same well-known amor cognitionis concept: “I loved Wisdom: I've searched for Her as a young man, willing to make her my bride, for I had been spellbound by Her beauty...” (Sap, Sol.:8, 2).
Pretty much in the same time with Sapientia Solomonis - dating around 37-41 A. D. - the embodiment of the Divine Wisdom as a woman had appeared in another apocryphal book The Wisdom of Ben Sirah. Under the undeniable authority of his legendary author (the rabbinical tradition calls Ben Sirah “the son of Jeremiah the Prophet”), this issue will have spread in the entire Jewish sapiential literature justified by the early Jewish literature as well (see The Book of Proverbs: 8-9). This was the impulse by which the semitic esoterism turned its face towards the hidden symbolism of Shir ha-Shirim (The Song of Songs). In fact, it might be argued that the entire medieval hermetism can be perceived as an encomium to the Mystical Union (unio mystica) between God and Man. However, the process that took symbols from the occultism to the bookshelf had literaturised this unio mentalis in the respect of Ben Sirah and Solomon erotic language: “Come to me, you who desire me, and eat your fill of my fruits. For the memory of me is sweeter than honey and the possession of me sweeter than the honeycomb” (Sirah: 24, 19-20).
From this epicenter, the Judeo-Christian occult tradition has given birth to the medieval cult of Madonna Intelligenza/ Madonna Angelicata, the one that was spreaded from Araby to Western Europe under the curtain of neoplatonic philosophy. The odyssey of this noetical symbol iterated the spreading of the She'kinah (literally: God's dwelling in the world), the feminine element of the Kabbalah's Deity, from the unwritten Jewish tradition to the European occultism. Dante refers once again to this marital cult and its metaphoric-mystical function, in his famous verse 3 from The Purgatory, Canto XXX, which is an apologetic footnote to the verse 4, 8 from Canticum Canticorum:

“Descend from Lebanon, celestial Spouse!
Thy Consort waits thee, to receive thy Vows!” (Purgatory, Canto XXX).

Around 1286, a few years before Dante started writing his exquisite poem (written between 1306 and 1321, Rabbi Moses ben Shemtov De Leon (who died in 1305) was just finishing the main part of Sepher ha-Zohar, the corpus of texts that was soon to become the supreme authority in the field of Jewish esoterism, some kind of Bible for the speculative kabbalists. In between 1295 and 1305 an anonymous disciple of Rabbi De Leon added other two arts to The Zohar's corpus of works: Ra'aia Mehemna (The Faithful Shepherd) and Tikune ha-Zohar (Addenda to the Zohar), where we find once again the theory of the four-fold meaning of The Torah. This theory had been exposed by R. Moses de Leon, as well as by R. Joseph ben Abraham Gikatilla the Thaumaturge (died after 1305) in his commentaries upon Maimonide's book Moreh Nebuchim (Guide for the Perplexed). According to all these authorities in the Kabbalah, there are four meanings covering the occult depths of the sacred books, a polysemantical approach maintained alive from the time of Pharaohs till their contemporaneity. Dante himself knew this esoteric theory and fixed it in his philosophical essay Il Convivio II, in the passage where he speaks about the four veils that should cover, in his interpretation, not only the sacred writings, but the profane ones too: “...si possono intendere e de onsi esponere massimamente per quattro sensi”.
Working in accordance with his polysemic theory we will find in the already quoted passage from The Paradise another introductio in abyssus of the Jewish occult tradition. In the Dante's syntagma “five-fold seven” letters, seen by the Florentine “as from a book within the astral spaces”, the author would to lead the reader, in our opinion, to the seven magical words that constitute the first verse of Pentateuch (also made up out of 35 letters), words by means of which, according to the Kabbalah (1), God has created the entire Universe. This polysemantical liminary verse of The Book of Genesis (Sepher Bereshit), had been clearly enough exposed in Tikunei Zohar (Rectifications of the Zohar), a volume of Zohar that contains 70 different interpretations of the first paragraph from The Bible.
These very few ways, not the only ones, in which Dante clearly meets the Jewish tradition are meant to prepare our rendering of the above quotation, in which the poet talk about “letters”, and about this weird “letter M”. The lyrics bring in – by means of an extremely convincing fashion – a highly important theory, from the very heart of the speculative Kabbalah, that shows how no sacred writings should be treated as a simple text, but – as Gikatilla says – as a texture ('ariga), through which one can perceive the great, absolute name of God, which is the final signature of all things.
In the Zohar (I:1a–2a), and in Tikunei Zohar as well (Tikun 49), the last letter, M (m sophit), from the divine name Elohim, one of the seven words that The Book of Genesis begins, becomes highly significant, being augmented by the kabbalistic letters-transposition method. Thus, according to a tradition that, says the Zohar, goes back to Elias the Prophet, the heavenly name Elohim, considered “the Mystery of all Mysteries”, the concentrated creative force sending its rays through everything that seeks expression and form in all worlds and through all languages, has to be understood as a composed syntagma containing the words Eleh (Hebrew, 'these' things) and Mi ('who') written in the opposite order, as im: “Just as מי (Mi) is combined with אלה (eleh), so the name אלהים (Elohim) is constantly polysemous. Through this mystery, the Universe exists”.
Based on this polysemy, a Great Arcana is linked in the Zohar by the name of God revealed in the first verse of Genesis, name that becomes for kabbalists a suggestive answer to the rhetorical question set out by Isaiah the Prophet: “Lift up your eyes on high, and behold who hath created these things (Mi bara eleh)?” (Isaiah 40:26).
Further on, let us fallow the interpretation assigned to R. Eliezar and R. Simeon in the introductory chapter of the Zohar:
"Lift up your eyes on high. Where? To the place whither all eyes are turned. There is the pathakh azeen, or 'opening of eyes'. There you will recognize the mysterious Ancient One who created these and is the object of research. And who is he? It is Mi (who) that is called the summit of the heavens above, for all things exist by his will. Because he is the object concealed and invisible after which all seek. Therefore is this mysterious being called Who (Mi), and beyond him search in vain. Rut at the other extremity is another being known as What! (Mah). What distinguishes the one from the other? Mi (who), the concealed and hidden One, is he whom all created beings are seeking to know, but after all their efforts and endeavors, by the gaining of knowledge, they only come at last to Mah (the what)...”(2)
Relayed on this interpretation, the Judeo-Christian occultists had made from letter M (Mi) a Supreme Arcana, which hides not only the secret name of God, but also a promise of reaching His work on earth, word (terram) that is also made out of six letters similar with Elohim and which still preserve the M like an impress of his divine Creator.
The indubitable sign providing that Dante knew all about the kabbalistic “mystery of day first” is this rather strange letter M from the passage quoted above, which letter indicates, in Florentine's case as well, almost explicitly, “their Bliss and Primal Good” (vide supra).
But the indubitable proof that the equality mark drawn between Dante's M and the Deity (as Deus sive Natura) is later given by the western esotericism. In a fairly independent fashion, other authors had used the same latter as a signum of the divine mystery. Thus, in his cosmosophy, Paracelsus – who studied Christian Kabbalah with Abbot Trithemius – the fundamental element is a mysterious principle M, “by means of which – he says – the Skies Themselves live. If not for It, They would all perish. We call it M, for nothing in this whole Universe had been created before It […] Therefore, you should carefully notice that what we mean by this M are not the things born out of Heaven, nor what emerges from there, neither what is sent forth by the Skies. One thing is sure, though, that this M maintains all the creatures, heavenly or earthly, and that, all the more, all the elements live in It and through It”(3).
Later on, during the Rosicrucian rave of 17th century, other voices will be still making clearly heard the shortest name of God, resuscitating the mystery of letter M. In the famous first manifesto of Rosycross Brotherhood, Fama Fraternitatis, published firstly in German, at Cassel, in 1614, the author speaks about a ”universal Book M” (Liber M: Das Buch der Welt), that is supposed to be one of the sacred books discovered in the crypt of the legendary founder of the Rosycross Brotherhood, Christian Rosenkreutz. This strange book – that exalted Paracelsus, according to the same Fama - presents in a dissimulated manner “the whole world's icon and pattern” (der kanzen Welt Bild und Gleichniss). It seams to be described here the same “book within the astral spaces”.
The analogy made by this key text, on which the whole Rosicrucian phenomenon was based, between the name of God (as the principium M) and an all comprising sacred book, goes back again to the speculations of Jewish Kabbalah. Some of the Jewish mystics, among which we mention here Ramban and Gikatilla, had perceived the entire text of Holly Book as a unique name of God. Taking the premise that the Torah was initially written without spaces between words, this theory has also given an impulse and an excuse for the letter-transmutations of the Kabbalah. Inasmuch us, after splitting the words, the Holy Book became a “succession of esoteric names” ('al dereh ha-shemot) that conceal “the path which leads to the mystery of the Supreme Wisdom” (acc. to Zohar I:145b).
From the rosicrucian bibliotheca philosophica, the Liber M moved on the John Heydon's treatise Holy Guide (London, 1662) with all the prestige requested by its Jewish origin: “we (the Rosicrucians) are in possession of a certain part of (Solomon's) work which is completely lost for you, that is the rosicrucian M, in which Solomon himself describes all the thing from the past, present and future” (sig. c 7 recto).
As F. W. C. Wingston had rightly observed, in 1888 already, Heydon's Holy Guide, reiterated through the rosicrucian filter certain baconian affirmations from The New Atlantis (1627). Describing his utopian community of Bensalem, where “Moses would have given the Law by means of a secret Kabbalah”, Bacon speaks in the same words with Haydon about a book of an old mysteries tradition that is studied in “the College of the Six Days” (allusion of The Bok of Genesis studied by the Zohar): “we have some parts of his (Solomon) works which for you are lost; namely, that Natural History which he wrote of all plants, from the cedar of Libanus (symbol of heavenly elevation) to the moss that growth out of the wall”. By replacing this Natural History book with his “rosicrucian M”, Haydon made a hermeneutic interpretation that denotes certain knowledge of occultism.
Let see in a short digression his possible arguments for this analogy made by Haydon between the rosicrucian book M and the the baconian encyclopedia of plant. In first of all we shall say that the mysteries tradition of the Occident has ever since included the occult botany between as subject matter. For example, the medieval followers of the practical path of esoteric Gnosis had the treatise of Nicolaus Damascenus: De plantiis (first century, the Arabic manuscript was discovered in a Masonic Lodge of Istanbul in 1923); the Stobaeus fragment included in Corpus Hermeticum as The Book of Hermes Trismegitus to Asclepius, to be Truly Wise (used by Prosper Alpinus in his De plantiis Ægyptii, Venetiis, 1592 - known by Shakespeare); or the Gershon ben Shlomoh's Sha'ar ha-Shamaiin (end of the 13th century). These all represents not only examples of an old and sacred science of Universe, but also the convincing efforts to provide a truly scientific basis for a modern botany. From the Middle Age up to the late rosicrucians this epistemological effort had the Christian theological support of an initiated, St. Clemens of Alexandria. One of his interpretations to a biblical verse (Exodus 33:13), interpolated with a passage of Sapientia Solomonis (7:17-20), made quite a career as an undoubted and expressive explanation of the ancient mysteries initiation and unveiling its secret objectives: ”The Wisdom of God Herself has shown me the true Gnosis of all beings, and made me become aware of the inner structure of the world [and of the properties of the elements, the beginning, the end and the middle of time, the alternative change of the solstice and the succession of the seasons, the way the year unfolds all through, the position of the stars, the nature of animals, and the instincts of all the wild beasts, the power of the spirits and people's thoughts, varieties of plants] and the virtues of all their roots“. According to Walther Woelker(4), this interpolated passage from Stromata II:5, 1, was a seminal text for entire Western Mystery Tradition. its influence being traced through many alchemical, astrological or kabbalistic texts, as, for instance, The Preface to Paraelsus' Prognosticatio eximi (1536), or Georg von Welling's Opus mago-cabbalisticum et theosophicum (1735). the last one with profound influences in Goethe's philosophy.
Exemplifying the experimental research of symbolical letter/principle M, as subject matter of a secret science, these books had influenced all the European esoteric institutions – from Dante's Fede Santa, going through Sodalitas Celtica of Trithemius and Paracelsus, up to Rosicrucians and the modern Speculative Masonry (with its famous “M words”). This subterranean stream has always accompanied the western history and has generated a hunger for knowledge which feeding the modern science with the limbs of a pantheistic and heretical divinity. In this marginal philosophy the letter/principle M hided a gnostic concept which have as starting point the confidence that the entire Universe is knowable as a “res addita” to essence. But only few adherents of this gnosiology knew, and Dante was one of them, that this letter M introduced in the West the first religious commandment from Judaism, which would have been, according to Maimonides, not to believe, but to achieve knowledge (l'eida), inasmuch as, the same Rambam said, “you cannot come even close to the contemplation of the divine things without having studied and understood first the sciences, the realities”(5). This gnostic attitude, with origins in Kabbalah, generated a scientific attitude inside the Western Occult Tradition, where the metaphysical knowledge was oriented to the final letter M from the divine name Elohim, also said not for “who” (Mi) had created, but for “what” (Ma) had He created. Thus it was opened an unlimited field for the positive and materialistic research that will seduce even the Catholic Church, which will admitted that “We believe in order that we may know; we do not know in order that we may believe” (Credimus ut cognoscamus, non cognoscimus ut credamus)(6).

Note
(1) See Zohar, I:15a, in The Zohar, Pritzker Edition, Vol. 1, translated & commented by Daniel C. Matt. For the esoteric meanings of these seven words see Chapter I:16 of Siphra Dtzenioutha, translated by S.L. Mac Gregor Mathers in Kabbalah Unveiled. Containing the Fallowing Books of the Zohar..., London, George Redway, 1887.
(2) Haqdamat Sepher Ha-Zohar 1:2a-2b.
(3) A. Ph. Theophrasti Paracelsi, De summis naturae mysteriis, Basilae, per Petrum Pernam, 1570, p. 81.
(4) W. Völker, Der wahre Gnostiker nach Clemens Alexandrinus, Berlin, Akademie-Verlag, 1952, p. 305.
(5) R. M. Maimonidis, Liber More Nebuchim, Basilae, J. Buxtorfio Fil., 1629, pars I, cap. V, p. 8.
(6) St. Augustin, Tractatus in Sanctum Joannem