According to Philo, the Therapeutae were widely distributed in the Ancient world, among the Greeks and beyond in the non-Greek world of the "Barbarians", with one of their major gathering points being in Alexandria, in the area of the Lake Mareotis:
"Now this class of persons may be met with in many places, for it was fitting that both Greece and the country of the barbarians should partake of whatever is perfectly good; and there is the greatest number of such men in Egypt, in every one of the districts, or nomes, as they are called, and especially around Alexandria; and from all quarters those who are the best of these therapeutae proceed on their pilgrimage to some most suitable place as if it were their country, which is beyond the Maereotic lake."
—Philo, Ascetics III
They lived chastely with utter simplicity; they "first of all laid down temperance as a sort of foundation for the soul to rest upon, proceed to build up other virtues on this foundation" (Philo). They were dedicated to the contemplative life, and their activities for six days of the week consisted of ascetic practices, fasting, solitary prayers and the study of the scriptures in their isolated cells, each with its separate holy sanctuary, and enclosed courtyard:
"the entire interval from dawn to evening is given up by them to spiritual exercises. For they read the holy scriptures and draw out in thought and allegory their ancestral philosophy, since they regard the literal meanings as symbols of an inner and hidden nature revealing itself in covert ideas."
—Philo, para. 28
In addition to the Pentateuch, the Prophets and Psalms they possessed arcane writings of their own tradition, including formulae for numerological and allegorical interpretations.
They renounced property and followed severe discipline:
"These men abandon their property without being influenced by any predominant attraction, and flee without even turning their heads back again."
—Philo para. 18
They "professed an art of healing superior to that practiced in the cities" Philo notes, and the reader must be reminded of the reputation as a healer Saint Anthony possessed among his 4th-century contemporaries, who flocked out from Alexandria to reach him.
On the seventh day the Therapeutae met in a meeting house, the men on one side of an open partition, the women modestly on the other, to hear discourses. Once in seven weeks they meet for a night-long vigil after a banquet where they served one another, for "they are not waited on by slaves, because they deem any possession of servants whatever to be contrary to nature. For she has begotten all men alike free" (Philo, para.70) and sing antiphonal hymns until dawn.