Quintilian, and J.S. Watson. Institutes of Oratory. Edited by Lee Honeycutt, 2010. Kindle Electronic Edition. Book 12 Chapter 6.
Quintilian discusses the appropriate age for an orator to carry on cases in public in book 12 chapter 6. He notes that many orators have begun public cases at an early age (Quintilian XII.6.1). However, maturity is required of an orator (Quintilian XII.6.2). This does not mean that one must reach an advanced age before working as an orator. “If we estimate the two separately, practice without learning will be of more avail than learning without practice” (Quintilian XII.6.4). It is important that the orator, at first, practice with cases which are not too difficult (Quintilian XII.6.6). This can spur the young speaker to refine his skills more until he is fully mature.