The organ repertoire is among the largest for any solo musical instrument. Because of the  organ's (or pipe organ's) prominence in worship in Western Europe from the Middle Ages on, a significant portion of organ repertoire is sacred in nature. The organ's suitability for improvisation by a single performer is well adapted to this liturgical role and has allowed many blind organists to achieve fame; it also accounts for the relatively late emergence of written compositions for the instrument in the Renaissance. Although instruments are still disallowed in most Eastern churches, organs have found their way into a few synagogues as well as secular venues were organ recitals take place.