In Percy Bysshe Shelley's own words, poetry can be considered "the expression of the imagination," and, therefore, a poet can be considered one who expresses his/her imagination well (Shelley, "A Defence of Poetry"). Shelley also defines imagination as the ability to use one's mind to "color [thoughts] with [the mind's] own light" in a way that yields brand new thoughts. Both of Shelley's poems "Ode to the West Wind" and "To a Skylark" are about nature, more specifically the everyday seen occurrences of the wind blowing and of a skylark singing where it can't be seen. Looking at both of these poems, we can say that one of Shelley's weaknesses is unimaginative subject matter. However, he is also capable of taking the ordinary subject matter of nature and "coloring" it in a way that nature teaches a lesson about poetry and about human nature. In that way, one of Shelley's strengths is his ability to take the ordinary and use beautiful imagery and other literary devices to make a brand new claim about the ordinary.
Shelley uses "Ode to the West Wind" to describe the wind blowing during a storm in the fall. He sees this wind as being both destructive and able to preserve and even links the wind to mankind's ability to think. More specifically, he sees the wind as being part of the process that makes nature regenerate each year, as we see when he calls the wind one "[w]ho chariotest to their dark wintry bed / The winged seeds, where they lie cold and low ... until / Thine azure sister of Spring shall blow" (I.6-9). In other words, he is seeing the wind as responsible for distributing and planting seeds to grow into plants in the springtime, which is nature's way of rejuvenating. He then wishes that the words of his poetry could be swept away by the wind so that his dead words could generate new birth, as we see in his final stanza. It seems that he is understanding the inanimate words of his poetry to be "dead thoughts," and just like dead leaves and dead debris act as fertilizer to bring things to life in the spring, he is wishing that his own dead words will bring the world to life. One issue with this poem is that the topics of wind and the rejuvenation of nature are very typical and unimaginative topics. It also seems quite common and unimaginative for a poet to say he wishes his words could be spread throughout the world to enlighten the world. However, he does speak of these mundane and imaginative topics using very beautiful images, metaphors, similes, and allusions.
The same can be seen in "To a Skylark," which is merely a poem about a skylark singing someplace where the poet cannot see the bird. Being unable to see the bird peaked Shelley's imagination to envision where the bird is, what it looks like, and what it's doing. He then likens the singing bird to a poet and to mankind in general, ending with the argument that mankind can learn a lot from a songbird who sings out of joy felt for no apparent reason. Again, a songbird is a very typical unimaginative topic. However, likening the songbird to mankind creates a very nice argument and moral commanding human beings to act joyously despite any contrary circumstances. What's more, again Shelley spoke of his mundane topic using very beautiful imagery, metaphors, and similes.
Both of these poems speak of the poet's longing to experience the mysteries of nature and his frustration at not being able to articulate to the world what only nature can express.
In "Ode to the West Wind," Shelley personifies the wind, which carries the autumn leaves and drives the clouds and the waves. The wind is uncontrollable and "The sapless foliage of the ocean / know Thy voice, and suddenly grow grey with fear"--an effect the poet strives to echo in his verse. The poet reflects that as a child his imagination seemed capable of racing along with the wind, and he pleads: "Oh! lift me as a wave, a leaf, a cloud!" Yet the poet has an exchange to make with the wind, an acknowledgement that poetry has its own incantatory power: "Scatter... my words among mankind! Be through my lips ...The trumpet of a prophecy!"
In To a Skylark, Shelley addresses a songbird, who reveals his joy in life "In profuse strains of unpremeditated art." Metered poetry is extremely hard to write, and the subjects of the poet's imagination are overshadowed with sadness, pain, and the satiety of love. The poet cannot ever match the "hymns" the skylark composes so effortlessly, yet he also recognizes that human minds require human words to express human experience: "Our sweetest songs are those that tell of saddest thought." Shelley admits that even without the downside of human experience, the joy of the "blithe spirit" is beyond his comprehension. Yet, knowing his own strengths as a poet, he says: "Teach me half the gladness / That thy brain must know, / Such harmonious madness / From my lips would flow / The world should listen then."