While the inscription is over the gates of Hell, they first enter the vestibule, that place reserved for those who did not use their intellect to choose God.
The inscription over the gate of Hell has a powerful impact: "Abandon every hope, all ye who enter here." Dante naturally thinks this applies also to him, and in the first of many passages that cause Dante anguish, Virgil smiles and reassures him.
The inscription above the gates of Hell implies the horror of total despair. It suggests that anyone may enter into Hell at any time, and then all hope is lost. Dante cries out that this sentence is difficult for him to bear. However, this condemnation does not apply to Dante, because, allegorically, he can still achieve salvation, and realistically, he is not yet dead so it does not (necessarily) apply to him.
Dante, in this early canto, is moved to tears and terror at his first sight of Hell. He continues to be moved until he learns, later, to be unsympathetic towards sin in any form. This is part of his learning process and his character development throughout the poem. Dante learns that sin is not to be pitied; however, this lesson takes him many circles of Hell to learn.
In Canto III, Dante sets up the intellectual structure of Hell. Hell is the place for those who deliberately, intellectually, and consciously chose an evil way of life, whereas Paradise is a place of reward for those who consciously chose a righteous way of life. Therefore, if Hell is the place for people who made deliberate and intentional wrong choices, there must be a place for those people who refused to choose either evil or good. The entrance of Hell is the proper place for those people who refused to make a choice. People who reside in Hell’s vestibule are the uncommitted of the world, and having been indecisive in life—that is, never making a choice for themselves—they are constantly stung into movement.
This explanation is the first example of the law of retribution, as applied by Dante, where the uncommitted race endlessly after a wavering (and blank) banner. Because they were unwilling to shed their blood for any worthy cause in life, their blood is shed unwillingly, falling to the ground as food for worms.
Among the sinners are the fallen angels who refused to commit themselves to either God or Lucifer and stayed neutral. However, a refusal to choose is a choice, an idea Dante uses that has since become central in existentialist philosophy.
Dante spies Pope Celestine V, who "made the great refusal" of giving up the chair of Peter after only five months, thereby clearing the way for Boniface VIII, to whom Dante was an implacable enemy. Celestine preferred to return to the obscurity of non-commitment, rather than face the problems of the papacy.
When Charon refuses to take Dante across the river, he does so because his job is to take only the dead who have no chance of salvation. Dante, however, is both a living man and one who still has the possibility of achieving salvation.
Virgil's incantation, "Thus it is willed there, where what is willed can be done," is a roundabout way to avoid the word "Heaven," which is repeated in Canto V. In later cantos, Dante uses other allusions of various kinds.
The shore of the river Acheron that serves as the outer border of Hell is crowded with more souls than Dante believed possible. These souls are propelled not by the anger of Charon alone, but by the sharp prod of Divine Justice, until they desire to make the crossing. Choosing to cross the river is their final choice, just as their desire for sin on Earth was also their choice.
