Musically, "Sabbath Bloody Sabbath" pushed the band's own established limits and the boundaries of heavy music at the time. The song features a complex structure with distinct sections, shifting dramatically from the crushing, heavy main riff to a much lighter, acoustic-driven middle section, before returning to an even heavier, sludgy outro riff. This dynamic range and intricate arrangement, incorporating layers and textures beyond their previous work, showcased a new level of musical ambition. While perhaps not a "limit" in the sense of restriction, this complexity challenged the band's compositional and performance capabilities, expanding their sound significantly beyond the raw, blues-based doom of their earlier albums into more progressive territory.

Musically, "Snowblind" exemplifies Black Sabbath's signature heavy sound, built upon Tony Iommi's powerful and sludgy guitar riffs. The song features shifts in tempo and dynamics, moving between heavy, driving verses and a more melodic, almost melancholic bridge section before returning to its powerful main riff. Geezer Butler's prominent bass lines provide a thick low-end foundation, while Bill Ward's drumming is both heavy and intricate, locking in perfectly with Iommi's guitar. Ozzy Osbourne's distinctive, haunting vocals deliver the lyrics with a sense of both exhilaration and despair, capturing the duality of the drug experience described in the song. "Snowblind" remains a fan favorite and a key track in the Black Sabbath catalogue, representing the dark, heavy, and often personal themes the band explored.

The lyrical meaning of "Fairies Wear Boots" has been subject to different interpretations over the years. One common theory suggests the song recounts a hallucinatory experience induced by drugs, likely LSD, where the narrator witnesses peculiar sights like fairies donning boots. However, bassist and primary lyricist Geezer Butler, along with vocalist Ozzy Osbourne, have also explained it stemmed from a real-life incident where the band members were harassed by skinheads. According to this version, the skinheads (known for wearing boots) called the long-haired band members "fairies," leading to the song's title and theme. This ambiguity, whether rooted in psychedelic visions or a confrontation with societal aggression, adds another layer to the song's enduring mystique within the heavy metal canon.

"Black Sabbath" served not only as the band's namesake (they changed their name from Earth after writing the song, inspired by the 1963 Boris Karloff horror film of the same name) but also as their sonic manifesto. It marked a distinct departure from blues-rock, establishing the template for heavy metal with its slow, crushing heaviness, reliance on powerful guitar riffs, and embrace of occult and horror-inspired themes. Widely considered one of the very first heavy metal songs, and arguably the first doom metal track, its impact was profound. It defined Black Sabbath's groundbreaking sound and paved the way for countless bands, solidifying its place as a landmark recording in rock history, often cited by critics and musicians as one of the most important and influential heavy metal songs ever recorded.

"Paranoid," the title track from their second album, became Black Sabbath's signature song and one of the most recognizable anthems in hard rock. Legend has it that the song was written hastily in the studio as filler material needed to round out the album's length, composed in mere minutes. Despite its quick conception, its driving proto-punk tempo, instantly memorable main riff, anxious lyrics depicting mental distress, and raw energy propelled it to become a major hit single, reaching number 4 on the UK charts. "Paranoid" showcased a slightly faster, more direct style compared to some of the band's slower, doomier tracks, proving their versatility and cementing its place as an enduring classic often cited as a key influence on both heavy metal and punk rock.

"Iron Man," a standout track from their second album Paranoid, is arguably Black Sabbath's most iconic song. It is immediately recognizable by Tony Iommi's simple, yet crushingly heavy and sludgy opening guitar riff, frequently cited as one of the greatest and most definitive riffs in rock history. The song's lyrics, penned by Geezer Butler, tell a science-fiction story about a man who travels into the future, witnesses the apocalypse, and is turned into steel upon his return while trying to warn mankind. Ignored and mocked, he eventually takes his revenge, fulfilling the prophecy of destruction he foresaw. The combination of this compelling, almost tragic narrative, Osbourne's distorted vocal delivery ("I AM IRON MAN!"), and the sheer power of the instrumental track has made "Iron Man" an enduring anthem of heavy metal and a cornerstone of Black Sabbath's legacy.

Lyrically, "Supernaut" ventures into themes of space travel and cosmic experience, fitting the somewhat sci-fi implied title, although Ozzy Osbourne's vocals deliver the lines with a sense of raw power rather than specific narrative detail. The song is often cited by musicians and fans alike as a quintessential Black Sabbath track and a cornerstone of heavy metal. Its influence can be heard in countless bands that followed, drawn to its combination of sheer heaviness and infectious rhythm. Notably, Frank Zappa famously declared the "Supernaut" riff as one of his all-time favorites, highlighting its impact beyond the confines of the metal genre.

Musically, "Sweet Leaf" is a cornerstone of the heavy, sludgy sound Sabbath pioneered, which would later heavily influence the stoner rock and doom metal genres. Tony Iommi's main guitar riff is monolithic – thick, heavy, and delivered with the down-tuned Gibson SG tone that became his signature. Geezer Butler's rumbling bass lines perfectly lock in with Bill Ward's powerful, deliberate drumming, creating an immense rhythmic foundation. Ozzy Osbourne's distinctive, yearning vocals glide over the massive instrumentation, delivering the pro-cannabis message with conviction. The song's combination of a simple, unforgettable riff, unambiguous lyrical content, and groundbreaking heaviness cemented its place as a classic rock staple and a defining moment in Black Sabbath's legendary catalogue.

"War Pigs," the opening track from their seminal 1970 album Paranoid, stands as one of Black Sabbath's most iconic and enduring songs. Originally titled "Walpurgis," the song is a powerful anti-war statement, condemning the politicians and generals ("war pigs") who orchestrate conflicts from afar while the poor are sent to fight and die. Geezer Butler's scathing lyrics paint a grim picture of war's devastation and the hypocrisy of those in power, resonating strongly with the anti-Vietnam War sentiment prevalent at the time. Musically, "War Pigs" features one of Tony Iommi's most recognizable riffs, a slow, menacing groove, and dramatic shifts in tempo, perfectly complementing the song's dark subject matter. Its extended length, iconic air-raid siren intro, and Osbourne's impassioned delivery have cemented its status as a timeless protest anthem and a staple of heavy metal music.

Despite common speculation that the title stands for "Nativity in Black," lyricist Geezer Butler has consistently stated its origin was far more prosaic. "N.I.B." was initially a nickname for drummer Bill Ward's beard, which Butler thought resembled a pen nib; the punctuation was added later for visual appeal. The lyrical content, however, is far from mundane. It's written from the perspective of Lucifer falling in love with a human woman, attempting to woo her by promising her the world and professing that his love has changed him. This portrayal adds a layer of complexity to the devil character, presenting him not just as evil, but as capable of love and persuasion, contributing significantly to Black Sabbath's dark mystique.