If the glacial dynamics of previous metal and hardcore abstractions Celestial and Oceanic didn't prove that Isis was a heavy band in every sense, then Panopticon should do the trick.

The title comes from 18th century philosopher Jeremy Bentham's prison design, which was later referenced by Michael Foucault in the 20th century.

The idea is that a centrally placed guard or watcher can keep track of a large number of prisoners, and it excited Bentham and concerned Foucault.

Heavy stuff for a metal band, huh? Both are quoted in the liner notes, bookended by aerial industrial photos laying out society's open sprawl.

It fits perfectly with the epic music on the disc itself, which is as angular as post-rock forefathers Slint and as cosmically expansive as Neurosis, yet closer to the intensity of hardcore than either of them.

Panopticon has the same cagey wall of noise as Oceanic, although the end product here is a little more polished.

Aaron Turner is still howling and growling, but he's less reluctant to actually sing, just as the music is more inclined to stretch out into Pink Floyd's velvet atmospherics, which were a part of Oceanic, too, but just not as pronounced as they are here.

Turner's lyrics are impenetrable, buried in the mix, but when they do pop through the haze of guitars and electronics they're appropriately weighty and tied to the omniscient paranoia of the title.