The Venerable Bede was a puer oblatus, a "boy oblate," sent to be raised at a monastery at the age of seven. The word oblate, in fact, means someone who has been offered. Monasteries that adhered to the Rule of St. Benedict accepted oblates that young—it was their chief source of new members—until 656CE, when the Tenth Council of Toledo forbade boys before the age of ten. Orderic Vitalis was given to his monastery at ten or eleven, and could take vows as early as fourteen. Archbishop Lanfranc of Canterbury suggested that oblates could take vows when the authorities of the monastery decided he was mature enough to understand and handle the obligations involved.
Various monasteries had their own policies regarding oblates. The 11th century About William of Hirschau defined two kinds of oblate:
—fratres barbati ("bearded brethren), also called conversi (converts), who took vows but did not have to be clean-shaven or live cloistered.
—oblati (oblates), workmen who followed religious rules while working at the monastery.
Other terms were used over the centuries: commissioned, donates, confronter, with various distinctions that changed over time. Despite the many approaches to managing and designating those who wished to be involved in the monastic or priestly life, the chief distinction was between those who entered fully and took all vows, and those who were only partially committed.
Which leads me to a new idea about oblates: a third order, for lay members of religious orders. There is a long history of this, which I'll tell you about tomorrow.