In searching for an ancient philosopher whose works have all been lost one turns instinctively to Diogenes Laertius to find a biography; but for the Peripatetic Aristo of Ceos—alas—there is none. Diogenes’ series of Peripatetic lives stops just short of Aristo, with his older associate, Lyco. There are, however, a few references to him, in Diogenes and various other authors. These references, collected by Fritz Wehrli in 1952, have served as the basis for current accounts of Aristo’s writings, apophthegms, philosophical thought, and his role in the Peripatos. 1 Wehrli himself in his commentary to his edition and in his 1968 article in Pauly-Wissowa laid the foundation for the present day portrait of Aristo. Subsequent accounts have followed with few modifications. From Wehrli’s collection of texts we might sketch a portrait like the following: Aristo of Ceos was an associate of Lyco of Troas in the Peripatos and his successor after his death. He was the author of many writings, among which were Lyco, Erotic Examples, On Relieving Arrogance, a work on old age, and quite possibly a few more whose titles ended up in a bibliography of a Stoic philosopher of the same name. He also wrote a history of philosophy or biographies of earlier philosophers, 180including the leaders of the Peripatos, in which he preserved the wills of his predecessors. In addition, he apparently wrote about politics, laws, and education. References to these writings allow us to construct at least a modest outline of his contributions to the history of the Peripatos during the last quarter of the third century BCE. That is not much; but the light it sheds on an obscure period is welcome. Yet there remains a nagging suspicion that we may know less than we think. 2