Quintilian, and J.S. Watson. Institutes of Oratory.Edited by Lee Honeycutt, 2010. Kindle Electronic Edition. Book V Chapter 12.
As Quintilian has detailed various kinds of proofs, here he summarizes how proofs should be used. Some proofs may well be doubtful, at least when used alone (Quintilian V.2.2). These must be brought forward with other proofs which lead to a comprehensive and reliable case. Other arguments are very strong by themselves and will stand independently (Quintilian V.12.6). Quintilian further mentions arguments which appeal to feelings (παθητικός). These are very powerful when used well (Quintilian V.12.9). While some suggest placing the strongest arguments first and others the weakest first, Quintilian prefers to chose based on the dynamic of the entire case (Quintilian V.12.14).
Quintilian digresses (V.12.17) to discuss the decline of serious argument in his lifetime, comparing it to a decline in general manliness.