[...] Diogenes Laertius is the author of an ancient Greek "history of philosophy," a synthetic work titled "Lives of the Philosophers" and "Collection of Doctrines," in ten books, which, with the last being the philosopher Epicurus, refers to those who philosophized from the earliest times to the days under the scrutiny and control, in a relative manner, of the author. As inferred from the title of the work, Diogenes Laertius combines in his writing a few historical elements with many philosophical data of the individuals mentioned in his historical account. The informational material is checked for its reliability, as it is correlated with other sources: it is quantitatively uneven, that is, in a few cases extensive (as, for example, in the case of Epicurus, which covers the entire extent of the last [the tenth] book of Diogenes Laertius's writing), while in most it includes shorter references to individuals. This unevenness has, of course, its justification: the author of this historical record has his personal preferences, and from this perspective, the fluctuations in the chapters of his synthetic work can be justified. [...] (from the preface by Socrates Ch. Delivoyatzis)