Finally, a Catholic priest who knows his history.
The requirement of clerical celibacy was only uniformized in the Patiarchate of Rome after the schism, sometime in the early 12th century--1124 sticks in my mind. Before that, something like perpetual continence was required because of the common practice of celebrating daily Mass, and the requirement of continence the day before the celebration of Mass found in the Patriarchate's local disciplinary canons.
In the East, the corresponding disiplinary practice requires continence from Vespers through the celebration of Liturgy. (Which lead to the following amusing incident in one of the seminaries of Russia in the late 19th century: An archbishop (thus, himself a celibate and monk) was teaching a class, and came to the point where this discipline was explained. A young, very conventionally minded, seminarian suddenly stammered, '...but...Father Nikolai, back home...he celebrated Liturgy every day...you mean he and his wife never...'. The archbishop looked over his reading glasses at the seminarian and asked, 'And for what purpose did the Good Lord make the afternoon?')