PERIPATETIC, SCHOOL. - The followers of Aristotle were called οἱ ἐκ τοῦ περιπάτου in reference to the walk (περίπατος) of the Lyceum (the seat of the school), and περιπατητικοί (a word connected with περιπατεῖν) in reference to their custom (common also to other schools) of disputing while walking. This, at least, still seems the most plausible solution to the well-known etymological question that has arisen around the name.
In the history of the school itself (which was also called simply the "Peripatos") several periods must be distinguished. Among the Peripatetics of the first generation after Aristotle's death, the principal ones were Theophrastus of Eresus (v.), Eudemus of Rhodes (2nd half of the 4th century B.C.), Dicearchus of Messina (a versatile writer whose ἀκμή can be placed around 310 at the latest), Aristoxenus of Tarentum (b. between 375-60, a distinguished theorist of music), Clearchus of Soli, Demetrius of Phalerum (b. ca. 350 B.C.), a pupil of Theophrastus. The orientation that they gave to the school is characterized by extensive research in natural science, literary history, and varied erudition, as well as by treatises on popular ethics, at the expense of metaphysics. Of the Peripatetic production of the time there survive the Characters of Theophrastus, two botanical writings and a few other short scientific treatises by Theophrastus himself, the Elements of Harmony (Ἁρμονικά στοιχεῖα), a portion of the Elements of Rhythm (Ῥυθμικά στοιχεῖα) of Aristoxenus, and only fragments of other works. Among the lost writings of a philosophical character are the dialogues Κορινθικός and Λεσβικός of Dicearchus, in which the man of Messina denied the immortality of the soul. The same direction of the Peripatetic school is preserved, indeed accentuated, in the first part of the Hellenistic age. The Aristotelians continue to devote themselves actively to the sciences of nature and to the various fields of history. In philosophy, the most notable personality is that of Strato of Lampsacus, the "physicist," successor of Theophrastus as head of the school (which he held from 288-87 [or 287-86] until his death in 270-69 [or 269-68]). Strato deformed the doctrine of the Stagirite in a purely naturalistic sense, identifying God with natural necessity, and approaching the thought of Democritus (v.). A pupil of Strato was Aristarchus of Samos (d. after 264 B.C.), the astronomer who was the precursor of the Copernican heliocentric conception. Other Peripatetics of this period were Leon of the Troad (ca. 300-225 B.C.), head of the school for many years, Ariston of Ceos (3rd century B.C.), Critolaus of Phaselis (1st half of the 2nd century B.C.), Diodorus of Tyre (flourished in the first decades of the 2nd half of the 2nd century B.C.). Literary history and the history of philosophy were treated by Hermippus (3rd century B.C.), Sotion (author of a Διαδοχή τῶν φιλοσόφων written between 200 and 170 B.C.), Satyrus (3rd century B.C.), Heraclides Lembus (2nd century B.C.) and others. Much of the information we have about the Greek authors of the classical age goes back ultimately to the works of these men; and to the Peripatos is also due the formation of that particular literary genre which is biography. The Peripatetic school, however, suffered, as an institution, beginning with Leon, a decline from which it was not to rise again until the age of Andronicus.
In the 1st century B.C. there begins precisely a third phase, and a livelier splendor of the school itself. A fruitful and imposing erudite labor is carried out around the works of the Stagirite, which Andronicus of Rhodes (v.; around 70 B.C.), tenth or eleventh in the order of the heads of the school, collected, arranged, published in a new edition and commented upon. The imperial age is marked by a notable series of commentators on Aristotle, among whom the famous Alexander of Aphrodisias (v.; 2nd century A.D.) excelled, called the "second Aristotle," whose exegeses were destined to have a very strong influence also in the Middle Ages. Important studies were also dedicated to Aristotle by Boethus of Sidon (perhaps living in the Augustan age), author of a Commentary on the Categories, Ariston of Alexandria (1st half of the 1st century A.D., himself also a commentator on the Categories), Xenarchus of Seleucia (Augustan age) and the polygraph Nicolaus of Damascus (b. ca. 63 B.C.), Alexander of Aegeae (1st century A.D., teacher of Nero), Ptolemy Chennus (philosopher and grammarian who flourished ca. 100 A.D., author of a work on the life and writings of the Stagirite), Aspasius (1st half of the 2nd century A.D.), Adrastus of Aphrodisias (ca. 2nd half of the 2nd century A.D.), Herminus (2nd century A.D.). It should be noted that in this age interest in Aristotelian metaphysics and logic revives, to which the Hellenistic Peripatos had devoted little attention. And it is precisely at this time that Aristotelianism is given that configuration of an organic system with which it will be handed down to the Middle Ages. Meanwhile, while the Peripatetic school in general remains fairly orthodox and conservative with respect to the thought of the master, there are also representatives of an eclecticizing Aristotelianism, such as the author of the pseudo-Aristotelian writing Περὶ κόσμου (in which an attempt is made to reconcile Aristotle with the Stoa); such as the famous geographer and astronomer Claudius Ptolemy (2nd century A.D.); such as the physician Galen (v.).
One of the last ancient Peripatetics is Themistius (v.), author of Paraphrases of various writings of the Stagirite.