De conscribendis epistolis
 Vives begins by telling “Señor Idiáquez” to always consider the rhetorical situation for the letter, primarily evaluating the relationship of the writer to the recipient. The reason is that, as Saint Ambrose told Sabinus, "In a letter the image of the living presence emits its glow between persons distant from each other, and conversation committed to writing unites those who are separated from each other." Thus, it is not a speech delivered by an orator in a crowded assembly. Rather, it is a conversation. Vives then gives a history lesson on the letter in an attempt to show that the best letter writers of antiquity understood this conversational aspect of the letter. Vives states that the exordium of the letter is both the hardest to write and the most important part of the letter. It will color the reader’s reaction throughout the body of the letter. It is important to tailor this section to the recipient: Vives also gives instructions on how to vary the letter’s style according to genre. He covers letters of petition, instruction, congratulations, consolation, incentive, and shared interests. “We may write on every subject,” says Vives, but he focuses his attention on the most popular epistolary genres. Following the pattern Vives sets out in his discussion of the exordium, the bulk of De conscribendis epistolis covers the components of the letter and considerations for composition such as diction and addresses on superscriptions. Throughout this how-to section of the treatise, Vives offers examples and templates, which are “suitable for our use” in the 1530s, as he puts it.