In keeping with much of Wordsworth's poetic output, nature, and the joy of nature, is a key theme in this poem. In the opening stanzas, the speaker is remarking upon the "sweet voice" of the birds he hears singing, and he takes time to observe the "pleasant noise" of rushing waters which fills the air. The speaker notes that, while a storm had stricken the moor the previous night, now every creature is outside enjoying the sun, and "the sky rejoices" in the beautiful morning. The Traveller, too, feels his "heart" captured by the "joys" of the spring morning; he is conscious of his own delight at the beauties of nature.

However, the poet does not only express joy and delight in nature. He moves on to note that, sometimes, as high as one's heart soars when out in nature, it can drop equally far into despair for no apparent reason. This introduces the second major theme of the poem: depression and dejection. The speaker uses language such as "sadness," "blind," and "low" and alludes to the poet Thomas Chatterton to underline the fact that, as humans, sometimes our thoughts become despondent and can even run into "madness," even where there is no real reason for it.

The climax of the poem introduces its third, redemptive theme: the idea that we should respect the humble who maintain their "cheerfulness" despite the difficulty of their daily lives and that we should thank God for sending these people to us as "admonishments." The old man the speaker meets is described in terms which suggest he is not quite, or rather, beyond, human. He has been sent to the poet from "some far region"—by implication, heaven. God, the poet indicates, will always send us what we need: in his case, it is this leech-gatherer, whose work is physically difficult and extremely lonely but who nevertheless remains sound of mind and gentle of voice. For the poet to allow himself to wallow in sadness where there is no reason for it is for him to disrespect the beauties of God's creation: a better example for him—and us—to follow would be that of the old man, who has very little but takes joy in what he does have.