The album represented a musical transition for Styx, as the band emphasized its pop sound more than the progressive rock influences that dominated their first eight studio albums. Peaking at #2, the album was Styx's highest album chart peak until its successor, 1981's Paradise Theatre, which hit #1. From a songwriting standpoint, Cornerstone is dominated by Dennis DeYoung and Tommy Shaw-- each is credited as sole songwriter or co-writer for five tracks on the album. Consistent with most of Styx's catalog from 1975 to 1983, DeYoung's contributions to Cornerstone found the most success on the charts. The first single to be released was also to become Styx's only US #1 single: "Babe", which DeYoung wrote as a birthday present for his wife Suzanne. The track was first performed and recorded as a demo with just him and the Panozzo brothers, but A&M executives heard the track and insisted it go on the album. Shaw overdubbed a guitar solo in the song's middle section. "First Time", another power ballad also written by DeYoung, was intended to be Cornerstone's second single. Shaw, however, expressed concern that releasing two ballads in a row would alienate the band's hard rock fan base. He felt strongly enough that he threatened to leave the band over the proposed release. The upbeat song "Why Me" was chosen instead, reaching #26 on the charts. The division was strong enough that DeYoung was briefly fired from the band, although he was invited back before word reached the press or public. Shaw's major contribution to the album was the folkish "Boat on the River", which became the band's biggest European hit. Shaw's other contributions included the pop-rocker "Never Say Never," the Shaw/DeYoung album-opener "Lights", the more progressively-flavored song "Love in the Midnight", and "Borrowed Time", a DeYoung/Shaw collaboration. James Young had one song on the album, the hard rocker "Eddie", which was aimed at Edward Kennedy, pleading with him not to make a run for the U.S. presidency. Young used a guitar-synthesizer solo. Instrumentally, the album demonstrated the shift to a more pop-oriented and organic sound. DeYoung predominantly used a Fender Rhodes electric piano on over half of the tracks, and the group used real horns and strings on the album on several tracks. While commercially successful, Cornerstonebrought to light the first fragmenting of the group's collective artistic vision. These divisions would continue to deepen, ultimately leading to Styx's dissolution following the release of the 1983 album, Kilroy Was Here.
