Quintilian, and J.S. Watson. Institutes of Oratory. Edited by Lee Honeycutt, 2010. Kindle Electronic Edition. Book 12 Chapter 11.
Quintilian closes his treatise by noting that the orator also reaches the end of a career (Quintilian XII.11.1). There is a time when age causes a decline in our abilities. It is best to retire before that is obvious to others (Quintilian XII.11.4). This does not mean the work is over. A retired orator can take on disciples (Quintilian XII.11.5). The work of teaching and coaching is rewarding in its own right. Quintilian himself found it so (Quintilian XII.11.8). However, the teacher must realize the student will not grasp everything immediately. Learning remains a process (Quintilian XII.11.11). Of greatest importance is the character of the orator (Quintilian XII.11.12). This is developed over time and by life experience. There is no substitute (Quintilian XII.11.18). Quintilian values the lifestyle of a learner. He lists many who serve as examples.