John Donne’s sonnet beginning “Oh my black soul” shows the effects of what might be called “Christian Platonism.” Plato’s ideas were very attractive to Renaissance Christians, partly because Plato emphasized the immortality of the soul and the existence of a world of eternal forms that transcended the ephemeral aspects of material reality.
Lines 3-4 of Donne’s sonnet seems particularly influenced by Plato’s ideas. Addressing his own soul, the speaker says,
Thou art like a pilgrim, which abroad hath done
Treason, and durst not turn to whence he is fled . . .
This phrasing recalls the Christian Platonic idea that the soul comes from God and heaven and ideally returns to God and heaven. Later language in the sonnet alludes to Platonic ideas that the soul is imprisoned in the body. The speaker in Donne’s poem hopes that his soul can escape this imprisonment and return to the eternal world from which it originally came. Ideas similar to this one are discussed at length in Plato’s Phaedo, a dialogue which immensely appealed to Renaissance Christians.