There is something complete about Stevie Wonder, and one senses that he is not only exceptionally important today, but will continue to be for as long as he chooses.

Sly Stone doesn't make good albums: only good records. His style is so infinite and revolves around so many crucial aspects that it has only come together perfectly on a handful of his singles.

'Call Me' is not an exceptional Al Green album, but it is as solid as a rock at its center.

'Band on the Run' is a carefully composed, intricately designed personal statement that will make it impossible for anyone to classify Paul McCartney as a mere stylist again.

The Rolling Stones are constantly changing, but beneath the changes they remain the most formal of rock bands. Their successive releases have been continuous extensions of their approach, not radical redefinitions, as has so often been the case with the Beatles.

As a performing group, the Beatles began by playing old rock favorites, for dancing, to tough audiences in Liverpool and Hamburg. When they began writing seriously, they discovered that they couldn't compose in the early American rock tradition.

Bob Dylan was the source of pop music's unpredictability in the Sixties. Never as big a record-seller as commonly imagined, his importance was first aesthetic and social, and then as an influence.