Mediæval Time

The monasterial rule (which before the general introduction of clocks was commonly followed by the mediæval public in the computation of time) divided the twenty-four hours of the day and night into seven parts (six of three hours each and one of six), the inception of which was denoted by the sound of the bells that summoned the clergy to the performance of the seven canonical offices i.e. Matins at 3 AM, Prime at 6 AM, Tierce at 9 AM, Sexte or Noonsong at Noon, None at 3 PM, Vespers or Evensong at 6 PM and Complines or Nightsong at 9 PM, and at the same time served the laity as a clock.
Time Canonical Office
03:00 Matins
06:00 Prime
09:00 Tierce
12:00 Sexte or Noonsong
15:00 None
18:00 Vespers or Evensong
21:00 Complines or Nightsong
The Decameron: The Classic Translation of John Payne, by Giovanni Boccaccio, John Payne (Translator)