The answer is largely monasticism and mendicancy. Nuns not clergy because not ordained but called the religious . *monks can become priests or bishops if they are ordained (can become regular clergy) ), deep immersion in prayer, and manual labor. Elements of asceticism in judaism but no previous model for monasticism. There was a long history of interior martyrdom (macrina for example) and the ideas of self-sacrifice were re-channeled. Idea went back to jesus many passages refer to storing up treasures only in heaven. It may have been a way to distinguish between inner and outer devotion as christianity became state mandated. For some, a true conversion could be seen by conversion to an ascetic life. St. pachomius (290-346) known as the founder: created the first monastery with a formal rule, by the time he died, he had founded 11 monastaries with 7,000 monks.