I think this was a short story I read in a magazine, probably at least 10+ years ago.
It roughly follows the point of view of a miner who appears to be part of some specifically bred mining/slave caste, possibly a clone. IIRC he is aware of no other life outside of mining, although somehow some of the clones have gotten their hands on William Blake's poetry. The phrase "Did he who made the lamb make thee" gets thrown around, I think.
Normally the clones(?) each recuperate from a work cycle in separate pods. But the protagonist, who is not fully developed yet, and an older clone sometimes share a pod and sync their breathing so they can fit together and talk about things (e.g. the nature of their world or poetry), although soon the protagonist will be too large to share a pod.
At some point (again IIRC) the protagonist manages to convince a group of the other clones to break out onto the surface, where they spout Blake poetry before being killed off by their oppressors.