Antithesis

Placing opposing ideas or words side by side, so that one illuminates the other through contrast.

In Paradise

you have made me glad, and so you make me clear, for, speaking, you moved me to doubt how, from a sweet seed, a bitter thing can come

"Sweet seed" and "bitter" are set against each other in the same sentence. The contrast of tastes condenses the whole question: how what is born of a generous father can come out miserly. The opposition makes the reader feel the problem before hearing the answer.

Cantos V to VIII: Mercury and Venus, Dante, to Charles Martel, formulating the doubt about lineage

but here we do not repent, we laugh, not at the fault, which does not return to the mind, but at the value that ordered and provided. Here one contemplates the art that adorns so much affection, and one discerns the good by which the world above makes the world below turn

Cantos IX to XII: Venus and the Sun, Folquet of Marseille, to Dante, in the heaven of Venus

but nonetheless, with every falsehood set aside, make manifest your whole vision; and let it scratch where the itch is. For if your voice is unpleasant to the first taste, it will later leave vital nourishment, once it is digested

Cantos XVII to XX: The prophecy and the Eagle, Cacciaguida, to Dante, on what he must write

for I saw and heard the beak speak, and in its voice "I" and "mine" sound, when in thought it was "we" and "ours"

Cantos XVII to XX: The prophecy and the Eagle, Dante, narrator, before the Eagle of Jupiter

now, my son, it was not the tasting of the wood that by itself was the cause of so long an exile, but only the passing beyond the sign

Cantos XXV to XXVIII: The three virtues and the Primum Mobile, Adam, to Dante, on the cause of the fall

the wound that Mary closed and anointed, the one so beautiful at her feet, is she who opened it and pricked it

Cantos XXIX to XXXIII: The Empyrean, Saint Bernard, to Dante, showing Eve in the rose