Serenity
Clarke tends to set her poems in serene places. The location provides a sense of serenity to the action. The narrator, young Clarke, of "Polar," for example, is surrounded by sleeping, immobile objects. Even her bear is asleep. Although Clarke devotes great thought to visually describing the scene of the sleeping child, she gives no hint of sound. Similarly, the subject of "In the Reading Room" is patiently scanning book titles. The action, here, is active, but silent and subtle. The ghost dancers of "The Titanic" also participate in active movement, even rigorous, but they are still ghosts. Despite their activity, they also benefit from the serenity of their underwater tomb. Their ethereal natures are reflected in the ghostly description of their dancing to the rhythm of the waves. Each of these poems rely upon the serenity of their physical settings to contrast with the narrator's actions in order to emphasize their nuance.
Nostalgia
Nostalgia is another common theme in Clarke's poetry. Whether in setting or subject, her poems all contain the element of backward progress through time. The settings of both "Polar" and "The Titanic" are past. Reflecting on a sweet memory of her own childhood, Clarke writes "Polar" in the present tense. "Long ago," being the key to understanding the entire poem. Reflecting upon a time she viscerally remembers napping with her toy bear, Clarke recreates the emotion of the scene by evoking her childish imagination. In their watery resting place, the ghost dancers of "The Titanic" are described participating in an eternal present. They have not died, but continue to celebrate aboard the ship. By giving the dead living actions, Clarke imbues them with life, animating the past. Although the setting of "In the Reading Room" contains no particular indication of nostalgia, the subject does. The narrator searches the volumes for a specific book, owned by a master. Since the narrator describes the author in such a manner, they place themselves in an inferior position, indicating relative youth. Thus the scene is of a young person desperately seeking out the memorialized wisdom of an elder.
Language
The essence of her craft, Clarke writes a great deal about language itself. Having learned Welsh in college as a means of defying her culture's embarrassment from oppression, Clarke possesses a dual understanding of the function of language. Her poem "Border" describes the various manifestations of language in daily life. For instance the first stanza pertains to the meaning of the word, hinting at the phenomenon of visually connotation of meaning. The second stanza addresses the sound of the word and its pronunciation in various different mouths. Finally she ends with the feeling which this word evokes in Clarke personally. The "border" which holds her back from the rest of society based upon racial prejudice also prevents Clarke from sharing what is meaningful about her experience. It's a boundary of thought as well as location.
Cruel Irony of Nature
Another significant theme is nature, specifically the ‘cruel irony’ of it. Several of Clarke’s poems are based around this aspect of nature. For example, in her poem White Roses about a boy who passes away from cancer, she discusses the way in which the “roses outlive the child.” The last stanza of this poem, after the boy has passed, discusses how “the sun carelessly shines after rain… (and the) cat tracks thrushes.” Nature, and life is almost careless of the dead, and it seems almost cruel that these habits of nature exist despite the tragedy that has just occurred, and these things like the roses, which tend to have short life spans, manage to outlive the boy.
We also see this concept of the ‘cruel-irony’ of nature in her poem Death of a Cat, where she recounts a memory concerning her dead cat. Her cat is buried “under the apple tree where fruit fattens,” and this is ironic as the cat has died, but it is buried in a place that brings forth so much life, and the cats’ death and decomposition will contribute to the life of the tree. Clarke does not take a side concerning this aspect of nature, she neither represents as something positive, nor as something negative. Instead, she represents it as what it is, and even though it can be sad, she understands that that is the way nature, and life work.
Motherhood
The theme of motherhood is another significant theme used by Clarke, specifically the relationship between mother and child. Clarke discusses this theme in several of her poems including Seal, Babysitter and Catrin, and she specifically focuses on both the beauty, and the difficulties involved in raising a child. For example, in her poem Babysitter, she uses the perspective of a babysitter to reveal the way in which a mother-child connection cannot ever be replaced. The babysitter is almost afraid of the child, fearing that “she will hate,” her, and she realizes that she is not her mother, and therefore cannot provide for her physically, nor emotionally. This represents the intimate, and irreplaceable connection between mother, and child.
Similarly, in the poem Catrin, involving an argument between mother and child, Clarke writes about the “red rope of love which we (characters) fought over.” This rope represents the physical connection, the umbilical cord tying a mother to her baby, but also the emotional, and deep-rooted connection between the two that helps them love one another, but also contributes to tension, and conflict. Through these poems, Clarke represents the theme of motherhood and both the intimate, and difficult parts involved with that.