The skylark isn't just presented by Shelley as a beautiful bird that sings sweetly. Its closeness to nature means that it can teach man how to recover that intimate connection to the natural world which he lost when he first entered into civilization.

As it is, however, the speaker compares man to the skylark and finds him wanting. Not even the most beautiful chorus of human voices—"Chorus Hymeneal"—can compare with the bird's sweet melody. This is because there's an innocence about the skylark that arises from his closeness to nature.

And that innocence can never be tainted by laziness, heartbreak, the contemplation of death, or any of the other afflictions that regularly torment humankind. Even our most sincere laughter is fraught with pain, as we constantly pine for what we do not have. This is why man's sweetest songs are tinged with sadness. The same cannot be said of the song of the skylark.

The poem ends with a passionate plea by the speaker for the skylark to transmit to him the secret, transcendent knowledge that he believes he must possess. The speaker is convinced that such knowledge, arising from the skylark's closeness to nature and manifested in his joyful song, can inspire poets like himself to write great, visionary works of "harmonious madness."

In Shelley's "To a Skylark," the poet contrasts man and the skylark. 

It should be noted that Shelley was considered one of the three major poets leading the Romantic Movement of literature, along with Keats and Lord Byron. Two earlier poets who brought these sensibilities into the 19th Century were Coleridge and Wordsworth.

There had been a growing interest in different types of poetry to do with three topics: nature, heightened feelings, and primitive cultures.

A great deal of their work reflected the movement's love and respect for nature, especially as the Industrial Revolution in Europe began to change the pastoral landscape.

Shelley's admiration of nature is evident in this poem. Some examples of the contrasts he draws between man and bird, follow.

Consider the first stanza:

That from Heaven, or near it,

                Pourest thy full heart

In profuse strains of unpremeditated art. (3-5)

Shelley notes that the creature must never have been a bird, but a "Spirit" that close to heaven can sing forth unscripted art so beautifully in the form of music. He writes that while man is earth-bound, the skylark can move closer to heaven to sing its praises.

Shelley writes:

Teach us, Sprite or Bird,

                What sweet thoughts are thine:

         I have never heard

                Praise of love or wine

That panted forth a flood of rapture so divine. (61-65)

He looks to the skylark (whether it be "Bird" or "Spirit") to teach him the bird's thoughts. He infers that man is not capable of such sounds of praise for he says that he has never heard anything before (either in praise of wine or love) that is equal to what the bird has shared in song.

In lines 76-80, Shelley describes emotional responses that humans have, saying that the bird would never express the same negative reactions:

With thy clear keen joyance

                Languor cannot be:

         Shadow of annoyance

                Never came near thee:

Thou lovest: but ne'er knew love's sad satiety.

"Languor" is listlessness or stagnation. This would be seen as a shortcoming in man, as would "annoyance." While he writes that the skylark must know of love, the bird's joy indicates that it has never experienced "satiety," which is defined as having been supplied with so much excess as to experience disgust or weariness. Obviously, Shelley sees the bird as a creature that could never tire of joy, while humans, even with the best of things, often grow tired of what they have. In this case, he speaks of the sadness one might feel having grown disinterested in love once it has been acquired. This gives the reader the idea that Shelley sees people as creatures that become bored with love.

While Shelley contemplates the differences between the bird and man, he more often seems disappointed with the shortcomings he attributes to people...but finds nothing that is not praiseworthy in the skylark.

How does the author contrast the life of the bird and the man in the poem "To a Skylark"?

In "To a Skylark," Percy Bysshe Shelley sets up a stark contrast between the life of a bird and the life of mankind. For the first half of the poem, the narrator focuses on the skylark itself, using simile and personification to present a sense of wonder at the sight of the bird. Midway through the poem, Shelley begins to contrast the experience of the bird with that of the narrator, saying:

Teach us, Sprite or Bird,

What sweet thoughts are thine:

I have never heard

Praise of love or wine

That panted forth a flood of rapture so divine.

Chorus Hymeneal,

Or triumphal chant,

Match'd with think would be all

But an empty vaunt,

A thing wherein we feel there is some hidden want. (61–70)

Here Shelley draws a clear distinction between the bird and man. To Shelley, the "sweet thoughts" of the bird are far more rapturous and "divine" than those of man (60). Further, even the greatest earthly choirs are "but an empty vaunt" when compared with the song of the skylark (69).

Shelley goes on to compare the double-edged sword of human experience with that of the skylark:

With thy clear keen joyance

Languor cannot be:

Shadow of annoyance

Never came near thee:

Thou lovest: but ne'er knew love's sad satiety.

Waking or asleep,

Thou of death must deem

Things more true and deep

Than we mortals dream,

Or how could thy notes flow in such a crystal stream?

We look before and after,

And pine for what is not:

Our sincerest laughter

With some pain is fraught;

Our sweetest songs are those that tell of saddest thought. (76–90)

For humans, love and laughter are always tinged with pain. Even the happiest experience will eventually be darkened by the specter of loss because of our understanding of life and death and our compulsion to "look before and after," rather than simply live in the moment (86). The speaker asserts that humans desire what they don't have; they lament the things they have lost, and human dreams are limited in their scope. However, for the skylark, love is simply love; the moment is the experience; there is no understanding of eventual loss. Because of this, their dreams are more "true and deep" that those of humans (83).

Shelley ends the poem yearning for "half the gladness" that the skylark knows. The contrast between bird and human is bittersweet. While we humans have a more nuanced understanding of life, the particulars of our understanding prevent us from experiencing life as completely as the skylark.