Published in 1840, 18 years after the author’s death, “A Defence of Poetry” is an 1821 essay by the English Romantic poet Percy Bysshe Shelley. Shelley wrote “A Defence of Poetry” in response to “The Four Ages of Poetry,” an essay by his friend Thomas Love Peacock.

In “The Four Ages of Poetry,” Peacock satirically argues that poetry is no longer needed amid the great technological and scientific advancements of the Industrial Age. He adds that poetry was once useful for awakening the intellect of society, but now humanity has advanced beyond it. Peacock also said the poets of his era were derivative, which showed the downfall of poetry.

Responding to Peacock’s critiques in “A Defence of Poetry,” Shelley argues that poetry is imperative to society. He does this by first differentiating between reason and imagination, and then he claims that reason serves imagination: “Reason is to imagination as the instrument to the agent, as the body to the spirit, as the shadow to the substance” (5).

Having established that reason is second to imagination, Shelley defines poetry as “the expression of the imagination” (5). He claims that all works of the imagination are poetry. Poets are critical to society because their works encapsulate universal truths and forecast a vision of the future for generations to come.

In the second half of the essay, Shelley explains the progression of poetry throughout history. From the beginning, poetry was a divine gift. Although they did not realize the magnitude of the gift, ancient poets had advantages over later poets because all the images and forms were fresh. They created the forms that later poets copied.

Because of the great gift poets have been given, Shelley says that poets should not argue for their own values of right and wrong because they are tied to the poets’ culture, time, and place. Instead, poets should strive to put forth universal truths.

In describing the history of poets, Shelley also repeatedly says that poets are not recognized as great in their own time, because they are for the future and not exclusively the present. Poets must submit to the sands of time to be recognized for their greatness.

Finally, poets must transcend their own time and place and work to be the legislators of mankind. By this, he means that poets’ influence extends beyond the realm of art and emotion. Through language, poets shape the social and linguistic order, thus paving the way for civil society. They must be a guide for the future because this is the true importance of poetry. To do that, poets must work on the harmony of language and the beauty of their poetry so that future generations will appreciate their work.

Without poetry, humanity would not have advanced, according to Shelley. While poetry is still around, humanity will advance into the future and not fall to corruption because “[p]oets are the unacknowledged legislators of the world” (54).