One reason Virgil serves as Dante's guide through Inferno is that Virgil represents an artistic hero to Dante—both the protagonist of the epic and the poet himself. Indeed, Virgil has long been considered by many the greatest poet of Italian antiquity, an opinion Dante holds. Dante calls Virgil "that well-spring, from which such copious floods of eloquence have issued," as well as "my master."

Dante has backslidden, though apparently more from inattention rather than a direct, willful act of disobedience against God. We do not know, however, if this inattention led him to commit specific sins that require restoration to the "path direct."

Dante personalizes the spiritual journey of The Inferno by presenting himself as the first-person protagonist. He is a middle-aged wanderer who lost his way and now finds himself on the wrong path—"Gone from the path direct"—in the dark forest. He doesn't remember how he lost his way, only that he was sleepy and unintentionally strayed from "the true path."

Virgil's situation—being stuck in Limbo—is a difficult dilemma. Because he is a good and just man, he does not get sent to hell to be punished; but because he is a pagan and not a Christian, he cannot go to Heaven.  Like all other good and just pagans, as well as infants who die before they are baptized, Virgil must remain eternally in the "holding tank" that is Limbo.

Another reference to Dante having left the right path, that is, the path that would lead him to a relationship with God.  A by-product of leaving the right path is that his senses are disordered.

In this case, to "con" is to study carefully. Dante has become very familiar with the Aeneid, which includes a long and detailed account of Aeneas' journey to the underworld to learn what the gods have in store for him and the Trojan race.

This is the first appearance of the Roman poet Virgil, Dante's guide to the Inferno and Purgatorio. Virgil (70–19 BCE), best known for the Aeneid, was born is a village near Mantua and lived in Rome during the reign of Julius Caesar and, later, Augustus Caesar.  Virgil, because he recounted Aeneas' journey through the underworld in the Aeniad, is an appropriate guide for Dante on the same journey.

Again, the lion, which represents insatiable hunger and ambition, is one of three animals mentioned in Jeremiah 5:6 that destroys sinners who remain unrepentant.

This reference to a panther is unclear at this point but could allude to one of three animals in the Book of Jeremiah—a lion, a wolf, and a leopard (panther)—that destroy sinners who fail to confess their sins.

This is Dante's way of indicating that he has strayed from the "path direct," or, in more conventional religious terms, the right way.  Straying from the right way may be emblematic of estrangement from God, which is why he finds himself in the selva oscura, the dark wood.

Virgil, a pagan who lived prior to Jesus's cleansing of sin, died unabsolved. Therefore, he is not allowed to enter the Kingdom of Heaven. Grace can only be given by God to Christian believers; it cannot be obtained either through virtue or reason. 

There is scholarly controversy over the meaning of Saint Peter's gate in this line. Many argue that the "gate" is the gate of Heaven, often referenced in the Bible and elsewhere in literature, but not in "Inferno." Therefore, the stronger argument is likely that the gate here is not to Heaven but to Purgatory, a gate that is actually mentioned in Dante's poem. 

Dante is referring to Beatrice, whose name means "one who makes blessed."  There was a "real" Beatrice, Beatrice Portinari (1255-1290), who was Dante's neighbor and with whom Dante fell deeply in love as an adolescent. She appears in Dante's 1295 poem "La Vita Nuova," wherein the poet extols her beauty and example of spiritual perfection.

Camilla was the daughter of the king of the Volscians. Nisus and Euryalus were young Trojan soldiers. Turnus was the king of the Rutulians.  All were leaders of indigenous Italians; enemies in life, here they are patriots, key elements in the founding of Rome.

The symbolism of the greyhound is one of the most contested elements of the entire work, attributed to various religious and historical figures as well as the second coming of Christ. However, the most frequent attribution is to the ruler Cangrande della Scala, who governed Verona from 1308 to 1329; his name suggests "Great Dog."

This is a reference to Aeneas, the Trojan price, son of the goddess Venus and the mortal Anchises. Aeneas sailed Italy following the fall of Troy (also known as Ilium) and became the legendary founder of Rome.

Virgil was born prior to the reign of Julius Caesar, who was assassinated when Virgil was in his mid-twenties.

The three beasts in this passage (the she-wolf, the leopard, and the lion) are among the most discussed and analyzed of the entire work. Most often, the she-wolf is said to symbolize lust; the leopard, pride; the lion, greed.  But they have also been said to stand for incontinence, violence, and fraud (respectively). These are the three primary categories of sin identified by Virgil in Canto XI. The appearance of these three symbolic animals foreshadows the broader structure of the journey Dante will take through the layers of Inferno.

From an astrological perspective, the sun is in Aries. It is the morning of Good Friday, the supposed time of creation, and thus Dante is flooded with a momentary feeling of beneficence.

One may interpret this line metaphorically as well as literally.  The feet were thought to be the limbs of the soul: the right symbolizing the will and the left symbolizing the intellect. Dante requires both in his journey.

The "planet" to which Dante refers is the sun. This reflects a pre-Copernican model (1543) of the cosmos, postulated by Claudius Ptolemy (100–170 CE), in which Earth was the fixed center of the universe.

Dante Alighieri (1265–1321) was thirty-five years old in 1300, the year the poem takes place.  the Bible's projection for a human lifespan was threescore years (sixty) and ten—seventy years. Thus, Dante-the-protagonist begins his journey when he is precisely "midway" through his life. Dante-the-author began composing the poem in 1308, when he was forty-three years old.