Dante's nine spheres of Heaven are the Moon, Mercury, Venus, the Sun, Mars, Jupiter, Saturn, the Fixed Stars, and the Primum Mobile. These are associated by Dante with the nine levels of the angelic hierarchy. Dante also relies on traditional associations, such as the one between Venus and romantic love. The first three spheres (which fall within the shadow of the Earth) are associated with deficient forms of Fortitude, Justice, and Temperance. The next four are associated with positive examples of Prudence, Fortitude, Justice, and Temperance; while Faith, Hope, and Love appear together in the eighth sphere.
First Sphere (The Moon: The Inconstant)
On visiting the Moon, Beatrice explains to Dante the reasons for the markings on its surface, describing a simple scientific experiment in optics. She also praises the experimental method in general (Canto II):
"Yet an experiment, were you to try it, could free you from your cavil, and the source of your arts' course springs from experiment."
The waxing and waning of the moon is associated with inconstancy. Consequently, the sphere of the Moon is that of souls who abandoned their vows, and so were deficient in the virtue of fortitude (Canto II). Here Dante and Beatrice meet Piccarda, sister of Dante's friend Forese Donati, who died shortly after being forcibly removed from her convent. They also meet Constance of Sicily, who (Dante believes) was forcibly removed from a convent to marry Henry VI (Canto III). Beatrice discourses on the freedom of the will, the sacredness of vows, and the importance of not collaborating with force (Canto IV):
"for will, if it resists, is never spent, but acts as nature acts when fire ascends, though force a thousand times tries to compel. So that, when will has yielded much or little, it has abetted force as these souls did: they could have fled back to their holy shelter."
Beatrice explains that a vow is a pact "drawn between a man / and God," in which a person freely offers up his free will as a gift to God. Vows should therefore not be taken lightly, and should be kept once given – unless keeping the vow would be a greater evil, as with Jephthah's and Agamemnon's sacrifice of their daughters (Canto V).
Second Sphere (Mercury: The Ambitious)
Because of its proximity to the sun, the planet Mercury is often difficult to see. Allegorically, the planet represents those who did good out of a desire for fame, but who, being ambitious, were deficient in the virtue of justice. Their earthly glory pales into insignificance beside the glory of God, just as Mercury pales into insignificance beside the sun. Here Dante meets the Emperor Justinian, who introduces himself with the words "Caesar I was and am Justinian," indicating that his personality remains, but that his earthly status no longer exists in Heaven (Canto V). Justinian recounts the history of the Roman Empire, mentioning, among others, Julius Caesar and Cleopatra; and bemoans the present state of Italy, given the conflict between Guelphs and Ghibellines, and the involvement of the "yellow lilies" of France (Canto VI):
"For some oppose the universal emblem with yellow lilies; others claim that emblem for party: it is hard to see who is worse. Let Ghibellines pursue their undertakings beneath another sign, for those who sever this sign and justice are bad followers."
By association, Beatrice discourses on the Incarnation and the Crucifixion of Christ, which occurred during Roman times (Canto VII).
Third Sphere (Venus: The Lovers)
The planet Venus (the Morning and Evening Star) is traditionally associated with the Goddess of Love, and so Dante makes this the planet of the lovers, who were deficient in the virtue of temperance (Canto VIII):
"The world, when still in peril, thought that, wheeling, in the third epicycle, Cyprian the fair sent down her rays of frenzied love, .. and gave the name of her with whom I have begun this canto, to the planet that is courted by the sun, at times behind her and at times in front."
Dante meets Charles Martel of Anjou, who was known to him, and who points out that a properly functioning society requires people of many different kinds. Such differences are illustrated by Cunizza da Romano (lover of Sordello), who is here in Heaven, while her brother Ezzelino III da Romano is in Hell, among the violent of the seventh circle.
The troubadour Folquet de Marseilles speaks of the temptations of love, and points out that (as was believed at the time) the cone of the Earth's shadow just touches the sphere of Venus. He condemns the city of Florence (planted, he says, by Satan) for producing that "damned flower" (the florin) which is responsible for the corruption of the Church, and he criticises the clergy for their focus on money, rather than on Scripture and the writings of the Church Fathers (Canto IX):
"Your city, which was planted by that one who was the first to turn against his Maker, the one whose envy cost us many tears produces and distributes the damned flower that turns both sheep and lambs from the true course, for of the shepherd it has made a wolf. For this the Gospel and the great Church Fathers are set aside and only the Decretals are studied as their margins clearly show. On these the pope and cardinals are intent. Their thoughts are never bent on Nazareth, where Gabriel's open wings were reverent."
Fourth Sphere (The Sun: The Wise)
Beyond the shadow of the Earth, Dante deals with positive examples of Prudence, Justice, Temperance, and Fortitude. Within the Sun, which is the Earth's source of illumination, Dante meets the greatest examples of prudence: the souls of the wise, who help to illuminate the world intellectually (Canto X). Initially, a circle of twelve bright lights dance around Dante and Beatrice. These are the souls of:
- Thomas Aquinas
- Albertus Magnus
- Peter Lombard
- King Solomon
- Dionysius the Areopagite, confused here with Pseudo-Dionysius
- Isidore of Seville
- Richard of Saint Victor
- Siger of Brabant
This list includes philosophers, theologians and a king, and has representatives from across Europe. Thomas Aquinas recounts the life of St. Francis of Assisi, and his love for "Lady Poverty" (Canto XI):
"Between Topino's stream and that which flows down from the hill the blessed Ubaldo chose, from a high peak there hangs a fertile slope; from there Perugia feels both heat and cold at Porta Sole, while behind it sorrow Nocera and Gualdo under their hard yoke. From this hillside, where it abates its rise, a sun was born into the world, much like this sun when it is climbing from the Ganges. Therefore let him who names this site not say Ascesi, which would be to say too little, but Orient, if he would name it rightly."
Twelve new bright lights appear, one of which is St. Bonaventure, a Franciscan, who recounts the life of St. Dominic, founder of the order to which Aquinas belonged. The two orders were not always friendly on earth, and having members of one order praising the founder of the other shows the love present in Heaven (Canto XII). The twenty-four bright lights revolve around Dante and Beatrice, singing of the Trinity, and Aquinas explains the surprising presence of King Solomon, who is placed here for kingly, rather than philosophical or mathematical wisdom (Cantos XIII and XIV):
"My words did not prevent your seeing clearly that it was as a king that he had asked for wisdom that would serve his royal task and not to know the number of the angels on high or, if combined with a contingent, necesse ever can produce necesse, or si est dare primum motum esse, or if, within a semicircle, one can draw a triangle with no right angle."
Fifth Sphere (Mars: The Warriors of the Faith)
The planet Mars is traditionally associated with the God of War, and so Dante makes this planet the home of the warriors of the Faith, who gave their lives for God, thereby displaying the virtue of fortitude. The millions of sparks of light that are the souls of these warriors form a Greek cross on the planet Mars, and Dante compares this cross to the Milky Way (Canto XIV):
"As, graced with lesser and with larger lights between the poles of the world, the Galaxy gleams so that even sages are perplexed; so, constellated in the depth of Mars, those rays described the venerable sign a circle's quadrants form where they are joined."
Dante says that sages are "perplexed" by the nature of the Milky Way, but in his Convivio, he had described its nature fairly well:
"What Aristotle said on this matter cannot be known with certainty.. In the Old Translation he says that the Galaxy is nothing but a multitude of fixed stars in that region, so small that we are unable to distinguish them from here below, though from them originates the appearance of that brightness which we call the Galaxy; this may be so, for the heaven in that region is denser, and therefore retains and throws back this light. Avicenna and Ptolemy seem to share this opinion with Aristotle."
Dante meets his ancestor Cacciaguida, who served in the Second Crusade. Cacciaguida praises the twelfth-century Republic of Florence, and bemoans the way in which the city has declined since those days (Cantos XV and XVI). The setting of the Divine Comedy in the year 1300, before Dante's exile, has allowed characters in the poem to "foretell" bad things for Dante. In response to a question from Dante, Cacciaguida speaks the truth bluntly. Dante will be exiled (Canto XVII):
"You shall leave everything you love most dearly: this is the arrow that the bow of exile shoots first. You are to know the bitter taste of others' bread, how salt it is, and know how hard a path it is for one who goes descending and ascending others' stairs."
However, Cacciaguida also charges Dante to write and tell the world all that he has seen of Hell, Purgatory, and Heaven. Finally, Dante sees some other warriors of the Faith, such as Joshua, Judas Maccabeus, Charlemagne, Roland, and Godfrey of Bouillon (Canto XVIII).
Sixth Sphere (Jupiter: The Just Rulers)
The planet Jupiter is traditionally associated with the king of the gods, so Dante makes this planet the home of the rulers who displayed justice. The souls here spell out the Latin for "Love justice, ye that judge the earth", after which the final "M" of that sentence is transformed into the shape of a giant imperial eagle (Canto XVIII):
"DILIGITE IUSTITIAM were the verb and noun that first appeared in that depiction; QUI IUDICATIS TERRAM followed after. Then, having formed the M of the fifth word, those spirits kept their order; Jupiter's silver, at that point, seemed embossed with gold."
Present in this sphere are David, Hezekiah, Trajan (converted to Christianity according to a medieval legend), Constantine, William II of Sicily, and (to Dante's amazement) Ripheus the Trojan, a pagan saved by the mercy of God. The souls forming the imperial eagle speak with one voice, and tell of God's justice (Cantos XIX and XX).
Seventh Sphere (Saturn: The Contemplatives)
The sphere of Saturn is that of the contemplatives, who embody temperance. Dante here meets Peter Damian, and discusses with him monasticism, the doctrine of predestination, and the sad state of the Church (Cantos XXI and XXII). Beatrice, who represents theology, becomes increasingly lovely here, indicating the contemplative's closer insight into the truth of God:
"She did not smile. Instead her speech to me began: Were I to smile, then you would be like Semele when she was turned to ashes, because, as you have seen, my loveliness which, even as we climb the steps of this eternal palace, blazes with more brightness were it not tempered here, would be so brilliant that, as it flashed, your mortal faculty would seem a branch a lightning bolt has cracked."
Eighth Sphere (The Fixed Stars: Faith, Hope, and Love)
The sphere of the Fixed Stars is the sphere of the church triumphant. From here (in fact, from the constellation Gemini, under which he was born), Dante looks back on the seven spheres he has visited, and on the Earth (Canto XXII):
"My eyes returned through all the seven spheres and saw this globe in such a way that I smiled at its scrawny image: I approve that judgment as the best, which holds this earth to be the least; and he whose thoughts are set elsewhere, can truly be called virtuous."
Here, Dante sees the Virgin Mary and other saints (Canto XXIII). St. Peter tests Dante on faith, asking what it is, and whether Dante has it. In response to Dante's reply, St. Peter asks Dante how he knows that the Bible is true, and (in an argument attributed to Augustine) Dante cites the miracle of the Church's growth from such humble beginnings (Canto XXIV):
"Say, who assures you that those works were real? came the reply. The very thing that needs proof no thing else attests these works to you.
I said: If without miracles the world was turned to Christianity, that is so great a miracle that, all the rest are not its hundredth part: for you were poor and hungry when you found the field and sowed the good plant once a vine and now a thorn."
St. James questions Dante on hope, and Beatrice vouches for his possession of it (Canto XXV):
"There is no child of the Church Militant who has more hope than he has, as is written within the Sun whose rays reach all our ranks: thus it is granted him to come from Egypt into Jerusalem that he have vision of it, before his term of warring ends."
Finally, St. John questions Dante on love. In his reply, Dante refers back to the concept of "twisted love" discussed in the Purgatorio (Canto XXVI):
"Thus I began again: My charity results from all those things whose bite can bring the heart to turn to God; the world's existence and mine, the death that He sustained that I might live, and that which is the hope of all believers, as it is my hope, together with living knowledge I have spoken of these drew me from the sea of twisted love and set me on the shore of the right love. The leaves enleaving all the garden of the Everlasting Gardener, I love according to the good He gave to them."
St. Peter then denounces Pope Boniface VIII in very strong terms, and says that, in his eyes, the Papal See stands empty (Canto XXVII).
Ninth Sphere (The Primum Mobile: The Angels)
The Primum Mobile ("first moved" sphere) is the last sphere of the physical universe. It is moved directly by God, and its motion causes all the spheres it encloses to move (Canto XXVII):
"This heaven has no other where than this: the mind of God, in which are kindled both the love that turns it and the force it rains. As in a circle, light and love enclose it, as it surrounds the rest and that enclosing, only He who encloses understands. No other heaven measures this sphere's motion, but it serves as the measure for the rest, even as half and fifth determine ten;"
The Primum Mobile is the abode of angels, and here Dante sees God as an intensely bright point of light surrounded by nine rings of angels (Canto XXVIII). Beatrice explains the creation of the universe, and the role of the angels, ending with a forceful criticism of the preachers of the day (Canto XXIX):
"Christ did not say to his first company: 'Go, and preach idle stories to the world; but he gave them the teaching that is truth, and truth alone was sounded when they spoke; and thus, to battle to enkindle faith, the Gospels served them as both shield and lance. But now men go to preach with jests and jeers, and just as long as they can raise a laugh, the cowl puffs up, and nothing more is asked. But such a bird nests in that cowl, that if the people saw it, they would recognize as lies the pardons in which they confide."