_Black Sabbath Vol. 4_ was the first album where classic sludge-rockers Black Sabbath (Ozzy Osbourne-vocals, Bill Ward-drums, Geezer Butler-bass and Toni Iommi-guitar) started experimenting – which possibly foreshadowed what would be more emphasized on the following album, _Sabbath, Bloody Sabbath_. I just want to make a clarification before I move on: Black Sabbath’s music is not about satanism or devil worshipping – it’s subject matter is mainly about the harsh realities of life (i.e., crime, war, drugs, mental illness and more), which is rather “dark”. Moving onto the tracks:The album opens with “Wheels Of Confusion/The Straightener”, which is a sludgy/heavy powerhouse. This is arguably the heaviest on the album. The lyrics are reflective and sad. “Tomorrow’s Dream” is a r&b-rocker with groove. “Changes” is a beautiful piano-based ballad. The combination of Ozzy Osbourne’s emotive vocals and the sad orchestral backdrops make this a somewhat painful track to listen to at times. “FX” is a short experiment featuring eerie guitar feedback from Toni Iommi. “Supernaut” (to me) proves that music is a transcendent force without limits or boundaries. The mix of boogie, classic psychedelic r&b and metal, shows that unlikely combinations can work – which almost makes it seem like it was never “unlikely” to begin with. “Snowblind” is a slow heavy rocker. Tony Iommi does some of his best soloing on this track. The end features some orchestral backdrops (possibly from synthesizers). “Cornucopia” is probably the most ominous sounding on here (check out the opening section). The dark lyrics contribute to this aspect as well. “Laguna Sunrise” is the beautiful and evocative acoustic guitar instrumental. If anyone were to listen to this calm, sedate and airy track (without knowledge of it being Sabbath), you wouldn’t guess that this was the same band known for their dark and sludgy output – that’s talent. “St. Vitus’ Dance” is an upbeat, summery and “happy” sounding rock track – at least on a musical (excluding lyrics) level. “Under The Sun/Everyday Comes And Goes” sounds the most “Sabbath-esque” on here. The beginning is heavy and ominous. It then segues into a straightforward heavy rocker. The lyrics are deep, thought-provoking and rebellious. They address such issues as religion, personal beliefs and violence.In short, _Black Sabbath Vol. 4_ is a classic metal album, which deserves to be owned by diehards, as well as those interested in Black Sabbath, or the roots of heavy metal. This would serve as a good introduction, as it features a well-crafted balance between heaviness and mild experimentation.