From the fourth century B.C. onward for at least eight centuries these 'Artists of Dionysus' were members of powerful guilds which bore that title [θυμελικὴ σύνοδος] together with the name of the city in which their headquarters were situated. These guilds made contracts with cities in their territories for furnishing theatrical exhibitions of every description and their members in many cases enjoyed freedom from military service and similar privileges, as well as the exemption from taxation. — Note 2, p. 356 of (Loeb) Diodorus Siculus (vol. II, Oldfather)