The Cyropaedia by the Athenian historian, philosopher, and soldier Xenophon, was originally written in the early 4th century B.C, to allow the author to lay out his political and moral philosophy. He did this by writing about the childhood of Cyrus the Great (founder of the first Persian Empire). Laying out the qualities of what he considered the ideal ruler, he attributed these to Cyrus, although it's not known if this portrayal was accurate or not. Translated by Henry Graham Dakyns, revised by F.M. Stawell,
Source and copyright Global Grey Ebooks: https://www.globalgreyebooks.com/index.html. The book can be downloaded from the Global Grey website.