In the '60s, when John Coltrane and Ornette Coleman were defining the concept of a jazz avant-garde, few knowledgeable observers would have guessed that in another 30 years the music's mainstream would virtually bypass their innovations, in favour of the hard bop style that free jazz had apparently supplanted. As it turned out, many listeners who had come to love jazz as a sophisticated manifestation of popular music were unable to accept the extreme esotericism of the avant-garde; their tastes were rooted in the core elements of "swing" and "blues," characteristics found in abundance in the music of the Jazz Messengers, the quintessential hard bop ensemble led by drummer Art Blakey.