September 14 was the 700th anniversary of the death of Dante Alighieri, the “father of the Italian language.” A year before his death, Dante completed The Divine Comedy, one the greatest epic poems in Western literature.

Here are nine things you should know about the work that has been considered one of the most essential books of mankind.

1. The poem is an allegory for the soul’s journey toward God.

The Divine Comedy is an epic poem divided into three parts (Inferno, Purgatorio, and Paradiso) in which the author is guided through nine circles of hell (Inferno in Italian) until he reaches Lucifer, then up the seven levels of the mountain of Purgatory (Purgatorio), and finally up through the nine spheres of Paradise (Paradiso).

Allegorically the poem represents the soul’s journey toward God, beginning with the recognition and rejection of sin in the Inferno, followed by the penitent Christian life in Purgatorio, which is then followed by the soul’s ascent to God in Paradiso.

2. The Divine Comedy wasn’t always divine and it’s not all that funny.

The original title of the poem was simply Commedia, which indicated that it was not written in courtly language and that it had a happy ending (the classical meaning of “comedy”). The Italian poet Boccaccio (1313–75) called the epic poem “Divine” because of its brilliant portrayal of religious themes. Since then, it has continuously been referred to as The Divine Comedy.

3. The poem contains more than 500 references to the Bible.

Although presented as a literary work, rather than a theological treatise, The Divine Comedy contains about 500 direct quotations and allusions to the Bible. “Very few writers, medieval or modern, ‘know their Bible’ as well as Dante did,” English scholar Edward Moore said in 1897. “This intimate knowledge is shown, not only by direct citation, but by the frequent interweaving of Scriptural allusion and phraseology into the fabric of his diction.” (The only Bible version Dante had access to was the Latin Vulgate, which included the apocryphal books, such as 2 Maccabees, which is the source for Roman Catholics’ doctrine of purgatory.)

4. In the poem, Dante meets dozens of people from the Bible.

Along his journey, Dante encounters almost 900 characters. Some of the people included his contemporaries, former politicians and world leaders, fictional characters, mythical beings, and heroes of antiquity. But he also meets a number of figures from the Bible, including Jesus, Adam, Cain, Abel, Absalom, Abraham, Achan, Caiaphas, Daniel, David, Elijah, Elisha, Ezekiel, Gideon, Jacob, Isaac, Jephthah, John the Baptist, John, Judas Iscariot, Leah, Levi, Luke, Mary, Matthias, Michal, Moses, Nimrod, Noah, Paul, Peter, Pilate, Rachel, Rehoboam, Saul, Simon Magus, and Solomon.

5. The number three (and its multiples) has a theological significance in the poem.

The number three (as well as its multiples) is a recurring number in the poem. There are three books (called canticles) that contain 33 cantos (a section of a long poem), and each canto consists of tercets (a form scheme of three verses). There are also nine Circles of Hell, three Wild Animals (lynx, lion and wolf), and three Guides (Virgil, Beatrice, and St. Bernard). This repeated use of three represents the Divine Trinity (Father, Son, and Holy Spirit).

6. The nine circles of hell in the Inferno represent various deadly sins.

The most influential part of the poem is indisputably the Inferno. In that section, Dante travels through nine circles in hell, each of which represents a different sin. The nine circles of hell in order of entrance and severity:

Limbo: For those who were otherwise moral but never knew about Jesus Christ. Dante encounters Ovid, Homer, Socrates, Aristotle, Julius Caesar, and more here.
Lust: The final destination of the lustful and adulterous. Dante encounters Achilles, Paris, Tristan, Cleopatra, and Dido, among others.
Gluttony: Where those who overindulge exist. Dante encounters ordinary people here, not characters from epic poems or gods from mythology.
Greed: Where those who loved money and materialism remain. Dante encounters more ordinary people.
Anger: The souls in this fifth circle include those who were easily angered, and those who were sullen or moody in their earthly life.
Heresy: The level for those who rejected orthodox Christian views. Dante meets Epicurus, Pope Anastasius II, and Emperor Frederick II.
Violence: This is the first circle to be further segmented into subcircles or rings. The Outer ring included those who were violent against people and property, such as Attila the Hun. The Middle Ring consists of those who commit violence against themselves (suicide). The Inner Ring is made up of blasphemers, or those who are violent against God and nature.
Fraud: This circle is distinguished from its predecessors by comprising those who consciously and willingly commit fraud. This level also included panderers and seducers; flatterers; simoniacs (those who sell ecclesiastical preferment); sorcerers, astrologers, and false prophets; corrupt politicians; hypocrites; thieves; false counselors and advisers; schismatics (those who separate religions to form new ones); and alchemists, counterfeiters, perjurers, impersonators, etc.
Treachery: The deepest circle of hell, where Satan resides. This level is divided into four parts. The first is Caina, named after Cain, who murdered his brother Abel, and is reserved for traitors to the family. The second, Antenora—from Antenor of Troy, who betrayed the Greeks—is reserved for political/national traitors. The third is Ptolomaea, for Ptolemy, who is known for inviting Simon Maccabaeus and his sons to dinner and then murdering them. The fourth round is Judecca, after Judas Iscariot, who betrayed Christ. This round is reserved for traitors to their lords, benefactors, and masters.

7. Dante fell in love with his muse when they were 9 years old.

Within the poem, the character of Beatrice represents divine revelation, theology, faith, and grace. This nearly divine figure leads Dante through most of the heavenly spheres. She was modeled on an Italian woman named Beatrice di Folco Portinari. Dante met her at a party when they were both 9 years old and instantly fell in love. His next—and final—encounter with her was nine years later, but by then he was pledged to marry another woman. Beatrice died eight years later at the age of 25.

8. The best-known line is an inscription on the entrance to hell.

The best-known line in the poem is the inscription over the gate of hell, which ends with the phrase “Lasciate ogne speranza, voi ch’intrate.” The most common translation into English is some version of “Abandon all hope, you who enter here.”

9. Dante’s poem has inspired a range of art and media, from symphonies to comic books.

Numerous musicians have been inspired by the poem, including classical composers Franz Liszt (Symphony to Dante’s Divina Commedia) and Pyotr Ilich Tchaikovsky (Francesca da Rimini, which is subtitled “Symphonic Fantasy After Dante”), and the electronica band Tangerine Dream (which released albums setting all three parts of the poem to music). Writers such as Chaucer, John Milton, and T. S. Eliot, have also found inspiration in Dante’s work, as have artists such as Salvador Dalí and Auguste Rodin (whose famous sculpture, The Thinker, was originally a component of a work called The Gates of Hell. The work has also inspired video games (such as the 2010 action game Dante’s Inferno) and comic books (such as 1980’s X-Men Annual #4, “Nightcrawler’s Inferno.”)