The distinction by Aristides Quintilianus (i, 18) between συμπλέκοντες and χωρίζοντες rhythmicians, does not draw a contrast between two rhythmical doctrines or between rhythmicians and metricians, but between the defenders of two methods of classifying rhythms according to two different rhythmical traditions. It is both exact and fruitful : it not only throws light on the lost part of Aristoxenus’ ῾Ρυθμικὰ στοιχεῖα (one of the main χωρίζοντες) and on the sources of Aristides Quintilianus’ rhythmical theory, but also enables us to classify almost mechanically all ancient testimonies about Greek and Roman rhythmics. Neither of these two traditions is homogeneous : among the χωρίζοντες, there are the canonicians (the mere arithmeticians), empiricists like Aristoxenus and the disciples of the dogmatic physician Herophilus; and, among the συμπλέκοντες, there are philosophers, rhetors, musicians and metricians. Finally, the orchestic tradition falls outside the dichotomy between χωρίζοντες and συμπλέκοντες. [http://booksandjournals.brillonline.com/content/journals/10.1163/22129758-12341030]