In 2000, a Beatles hits package of 27 songs, “1,” sold 12 million copies and parked itself at the top of the Billboard album charts. That improbable occurrence cemented the ability of the band's music to reach across generations.

So every few years, we revisit the works of those four musicians from England. But it hasn't been until “Eight Days a Week” that a possible explanation found its way into my head.

Music journalist and historian Jon Savage discusses the prolific nature of the band. In their touring years alone, they played 400 shows, released in excess of 100 songs, made two films, and did assorted promotional appearances on television and radio. (A pair of double CD sets, “Live at the BBC” and “On Air – Live at the BBC Volume 2,” collect close to 100 live radio performances.)

Savage compares The Beatles to Franz Schubert and Wolfgang Mozart. Mozart composed in excess of 600 pieces. He died at age 35 in 1791. Schubert wrote hundreds of pieces before his death at age 32, although very few were known before his death in 1828. Mozart at least enjoyed fame, if not fortune, in his time.

Savage remarks about the overwhelming quality of The Beatles' work, particularly given the band's brief lifespan.