Om is a band that plays heavy music, and in their music they sing about heavy things: "Empathy release me," goes one passage on Advaitic Songs, "and the phoenix rise triumphant. And walks onto the certitude ground-- the soul's submergence ends." As syntax, it's absurd. As content, it's absurd. That doesn't matter. What matters is Al Cisneros' delivery: sinister and premonitory, like an incantation to summon bad old things. Drums crash around him; cello and tamboura swirl. The distance between the truly awesome and the accidentally comedic in Om's music is always about a hairsbreadth.

For the sake of convenience, the band has always been classified as metal, but that's only for the sake of convenience. On Advaitic Songs, they cherrypick from Sufism, Catholicism, and Hinduism. One curious Yahoo! Answers user wonders if they are Satanic or Christian or Neither. Cisneros is deep into chess, and was formerly the bassist for stoner-metal paradigm Sleep, a band that wrote an entire 50-minute song called Dopesmoker. Om is not exactly metal; they're pan-global mystical music for the heavy-metal demographic.

Their first few albums, recorded exclusively by Cisneros and drummer Chris Hakius, were exercises in spreading as few notes over as much time as possible while still maintaining a clear, heavy groove. Part of what made them so powerful is how pared down they were. Ignore the shimmering Catholic icon paintings and the pan-Arab flourishes: If anything made Om's music religious, it was the sparseness of their sound, as committed and underfed as a monk.

Advaitic Songs, like 2009's God Is Good, incorporates instruments like tabla, cello, and flute (which, admittedly, is made of metal). The paradox about them is this: With two people, Om sounded expansive; with more, they sound comparatively weak. The music is unmistakably theirs, but the intensity of it feels lost in the arrangements. Listening to it, I worry that at any point I may be visited by southeast Asian violins. Diversity, it turns out, can be a diluting agent.

There is an argument here, an argument about minimalist art and how our brain processes not only sound, but information in general. The author David Foster Wallace wrote that one difference between fiction and non-fiction is that in fiction the writer works from "silence" while in non-fiction the writer works from "Total Noise, the seething static of every particular thing and experience." Give someone two or three slow-moving parts to focus on, and a quasi-meditative state ensues-- this is why meditations follow a single mantra designed to wipe the mind clean of any other distractions.

Om have always started from silence. Lumbering tempos, purity of purpose, and an ability to swing so hard and slow it sounds like they're struggling through water: This is why we came to them in the first place. Ornament and clutter: This is what we were trudging away from.