This poem takes up the refrain of love from the last line of “Earth’s Answer” and explicates two views on the nature of love. The “Clod of Clay” sees love as selfless and giving, building “a Heaven in Hells despair.” The hard “Pebble of the brook,” however, sees love as seeking “only Self to please” in order to eventually build “a Hell in Heavens despite.”
The love that has been bound by Reason, and which must be renewed in order to free Earth from her chains, is thus examined to ask if men love selflessly or selfishly. The difference in perspective aligns with the “experiences” of the two inanimate speakers. The clod has been “Trodden with the cattle’s feet,” so that it is malleable, but also easily shaped to the will of others. The pebble has been hardened by its time in the brook and therefore offers resistance to any who would seek to use it for their own ends. By contrast, the clod is somewhat mobile, whereas the pebble must remain at rest in its place on the bottom of the brook. Blake uses his ironic voice of experience to point out that love, if done according to the edicts of Reason, creates a Hell on earth, whereas selfless love—love from the heart and the ever-adapting Imagination—can make a Heaven out of the Hell surrounding mankind.
Nonetheless, the poem does not allow the reader to side completely with the Clod and its view of love. Both clod and pebble experience loss; the Pebble rejoices in the loss of others, while the Clod rejoices in its own loss of ease. Even the Clod's Heaven is built on the despair of Hell, thus "taking" from another in order to increase. In the "Experienced" mind, exploitation of others is a requirement for progress of any sort.
Structurally, the poem appears at first to be two balanced syllogisms of the respective viewpoints. The word “but” in line 6 is the turning point from the Clod's argument to that of the Pebble. The former argument is one of Innocence, while the second shifts to Experience. That Blake chooses to end the debate with the Pebble's argument lends to this poem an interpretation that favors the Pebble's hardened point of view regarding love. However, the balancing lines "And builds a Heaven in Hell's despair" (line 4) and "And builds a Hell in Heaven's despite" (line 12) force the reader to see the two views as balanced and to reach his own conclusions based on personal experience.