By 1977 England was in the throes of punk, a musical revolution that held hugely successful "dinosaur" rock groups in contempt. So ANIMALS, the album Pink Floyd released that year, found the band as musically stripped down as they'd ever been. The overabundance of soundscapes, ethereal synths and lush textures of the past gave way to a leaner, more guitar-driven Floyd.
Yet thematically, Waters and co. still reached for the sky. Inspired in part by George Orwell's classic novel, "Animal Farm", ANIMALS divides humans into three categories--dogs, pigs and sheep--and features each classification in song. The dogs are merciless opportunists, grasping for success at any price; the pigs are pathetic, self-righteous tyrants; and the sheep are the mindless followers, being used by the dogs and pigs. This anthropomorphising was Waters' view of the dehumanising side of capitalism. And befitting such a lofty theme was the length of the album's three main pieces--none shorter than ten minutes.
"Dogs" was co-written by David Gilmour, and it features some of his most inspired playing. The greed driving these dogs towards grander heights of materialism eventually leads to a solitary death from cancer, cloaked in an air of self-importance. "Pigs (Three Different Ones)" overflows with biting lyrics that scorn high-minded censors in general, and Mary Whitehouse (a self-appointed guardian of British pop music morality) specifically. The grunting of pigs precedes Waters' venomous delivery of each word, as Gilmour's scratchy playing and unsettling use of a Vocoder box become effective conduits for the song's malevolence.
"Sheep" starts out with the herd docilely grazing, blissfully unaware of the dogs lurking nearby. The sheep are led to the slaughter, before staging a revolt and killing off the dogs. The soundtrack of this defiance opens with Richard Wright's effect-free electric piano leading a galloping rhythm, before Waters' bass eases the group into a momentary lull. The pace picks up again, and Gilmour's slashing leads drive the song into a rousing climax, fading out with the peaceful sound of chirping birds.

1. Pigs On The Wing
2. Dogs
3. Pigs (Three Different Ones)
4. Sheep
5. Pigs On The Wing 2