the popularity of the lp ushered in the "album era" of english-language popular music, beginning in the 1960s, as performers took advantage of the longer playing time to create coherent themes or concept albums. "the rise of the lp as a form—as an artistic entity, as they used to say—has complicated how we perceive and remember what was once the most evanescent of the arts", robert christgau wrote in "" (1981). "the album may prove a '70s totem—briefer configurations were making a comeback by decade's end. but for the '70s it will remain the basic musical unit, and that's ok with me. i've found over the years that the long-playing record, with its twenty-minute sides and four-to-six compositions/performances per side, suits my habits of concentration perfectly."