1977 was not only the year of Star Wars, it also heralded the Age of Spirituality!  As a follow up to the recent post on Byzantium and Islam, a special exhibit from 2012 with a permanent web presence, I note here that the Metropolitan Museum of Art has made available for download a true monument of scholarship on early Christianity and Late Antiquity, produced in conjunction with one of the most important special exhibits ever (“hailed as one of the most important didactic exhibitions ever assembled by an art museum”), The Age of Spirituality: Late Antique and Early Christian Art, Third to Seventh Century (Nov. 19, 1977-Feb. 12 1978).  This massive (700+ pages) volume, with detailed descriptions of 450 works of art from 110 institutions and 15 countries, edited by the consultative curator Kurt Weitzmann, is arguably the most comprehensive reference work in the field; out of print, and with prices on Amazon ranging from $349.88 to $855.89, it can in fact be viewed for free, courtesy of the Met’s own press.

http://www.metmuseum.org/research/metpublications/Age_of_Spirituality_Late_Antique_and_Early_Christian_Art_Third_to_Seventh_Century