Benedict’s Rule (Chapter 63) seeks to establish some kind of differentiation without fostering rancor in the community. The simplest way to do it was by date of entry into the community.
Benedict wrote clearly, “The abbot is not to disturb the flock entrusted to him nor make any unjust arrangements” (63:2).
The abbot was free to carefully consider virtue in ordering the community, but the implication here is that the truly virtuous monks would be viewed as such by the larger community—thus not incurring any spirit of jealousy on their part or pride on the monk’s part.
I’ve spent nearly thirty years of my life robing up for academic processionals. We too follow ordering the line of march in relation to longevity—not understood in the hierarchial sense (“seniority” or “superiority”) but simply in terms of who has been around the longest.
When the ordering is truly holy—whether in a monastery or in a seminary—a beautiful thing happens, “the younger monks respect their seniors, and the seniors love their juniors” (63:10)