The most famous is "Give up all hope, you who enter," the last verse of the inscription over the gate of Hell, in Canto III. It comes from a gate that speaks in the first person and says it was made by justice, by power, by supreme wisdom and by primal love.
The final verse weighs less as a threat than as a definition: Hell is the place where there is nothing left to hope for. The inscription presents eternal punishment as the work of justice, and Dante reads it as a sentence he does not yet understand; Virgil responds with an order and a gesture, his hand and his cheerful face, without commenting on the verse.
Other lines of the poem circulate outside it. "There is no greater sorrow than to remember a happy time in misery," spoken by Francesca in Canto V. The opening of Canto I, "midway along the path of our life I found myself in a dark wood." And, in Canto XXVI, Ulysses's speech to his companions, "you were not made to live like brutes, but to pursue virtue and knowledge."
The last phrase of the cantica, in Canto XXXIV, is the one that most contrasts with the one on the gate: from there they came out "to see the stars again."