Terce, Sext, and None correspond to the third, sixth and ninth hours of the day, and thus follow Lauds which begins at sunrise, approximately 6:00 am. Terce is Latin for third, Sext means sixth, and None means ninth. In the primitive Church there is evidence that the apostles and early Christians prayed at these times, either in private or in common. The Acts of the Apostles and the post-scriptural document, the Didache of around 100 AD, also Saint Clement of Alexandria, Hippolytus of Rome and Tertullian of Carthage make mention of these prayer times. In the Old Testament, such as Daniel 6:10, we also find mention of such practice. There it is said that Daniel got “down on his knees three times a day to pray to his God and praise Him,” though some commentators would say this might be reflecting the Jewish custom of prayer at morning, noon and evening, rather than midmorning, midday and mid-afternoon.
In any case, the custom of Little Hours grew up in the monastic and larger Church in the course of the centuries and still is followed in some monasteries and hermitages. Saint Basil the Great mentions that these little hours are of a monastic origin and, but for the monks of Saint Pachomius prior to Basil, these offices were still prayed in private. It seems there was no universal practice of the communal recitation of these hours until the Middle Ages. These hours continue to be prayed by many religious communities to this day.