This historic collaboration brings full circle a process which began when promising young American musician Philip Glass met Indian master Ravi Shankar in Paris in 1965. That week Glass, studying with the great Nadia Boulanger, was earning pocket money doing notation and conducting a recording session for the soundtrack of Conrad Rook's film "Chappaqua." The score's composer, Ravi Shankar, was directing his ensemble from the sitar.

Unlike previous Shankar "collaborations" (actually elaborate sessions with masters of other musical traditions joining Ravi to "jam" on his own music) the Glass encounter was a rare instance of classical music reciprocity, each composer presenting thematic material to the other as raw material from which these finished pieces were fashioned. Passages contains four such co-ventures: two Glass compositions on themes by Shankar (Shankar / Glass); two Shankar compositions on themes by Glass (Glass / Shankar) as well as one piece from each composer completely of his own devising.