The first versions of Bruckner's symphonies often presented an instrumental, contrapuntal and rhythmic complexity (Brucknerian rhythm "2 + 3", use of quintuplets), the originality of which has not been understood and which were considered unperformable by the musicians. In order to make them "performable", the symphonies, except Symphonies No. 5, No. 6 and No. 7, have been revised several times. Consequently, there are several versions and editions, mainly of Symphonies 3, 4 and 8, which have been deeply emended by Bruckner's friends and associates, and it is not always possible to tell whether the emendations had Bruckner's direct authorization.