According to Levertov, writing poetry provided her an opportunity to discover and develop theological insights. The poems in The Stream and the Sapphire are signposts on her way to faith. The central theme in all these poems is the nature of faith, but Levertov combines this theme with discussions about doubt, aesthetics, imagination, and sainthood.
The most prominent theme in this collection is doubt and faith. Levertov usually depicts faith as a paradox, one dependent on intangibles for people living in a physical world. Some of her most stunning treatments of this theme can be found in “Human Being,” “Avowal,” “Variation on a Theme by Rilke,” and “Suspended.” In these poems she affirms her sense of being upheld by an intangible grace.
Another prominent theme in Levertov’s poems is her treatment of aesthetics and faith. Many of these poems began with aesthetic experiences, such as listening to a concert, viewing a painting, or attending a Mass. Some of her most prominent displays of this theme are “Candlemas,” “Agnus Dei” (taken from “Mass for the Day of Saint Thomas Didymus”), “Psalm Fragments (Schnittke String Trio),” and “The Servant-Girl at Emmaus” (based on a painting by Diego Velázquez). Such poems underscore Levertov’s realization that beauty—which is one of the three transcendentals in theology along with goodness and truth—can lead people to God. Levertov uses the Affirmative Way or Positive Way in approaching creation, seeing the love of people and creation as the beginning point for understanding God.
For Levertov, imagination is also a vital ingredient in faith. “On the Parables of the Mustard Seed” and “What the Figtree Said” are both fine examples of how imagination can function both as a tool for creating the poem and as a key to the Kingdom of God. Without imagination, the gifts from God are easily lost.
The theme of sainthood also plays a prominent role in Levertov’s poetry. Saints such as Mary, Simeon, Peter, Thomas Didymus, Brother Lawrence, Dame Julian of Norwich, and more contemporary spiritual leaders such as Thomas Merton and Dom Helder Camara, populate her poems. However, Levertov’s saints are paradoxically very human, having great doubts and fears while determining to be valiant for God.