The chronological indicators in this entry are mutually incompatible: some late fifth century BCE, others late fourth century. Either the Suda or its source has conflated two homonyms who should be kept distinct from each other (as they are in e.g. the Index nominum et rerum of R.D. Hicks' Loeb edition of the principal source used, Diogenes Laertius). One is the mathematician and geometer Theodorus of Cyrene (fl. late 5th century BCE), one of the characters in Plato's Theaetetus; a former disciple of the sophist Protagoras, and portrayed by Plato as an associate of Socrates and the teacher of Theaetetus; see generally OCD(4) Theodorus(2). The other, to whom most of the material applies, is the 'Cyrenaic' (Aristippean) philosopher Theodorus, mentioned briefly in OCD(4) under Cyrenaics.
[1] See Diogenes Laertius 2.86, 2.97. Theodorus appears to have written a book On the Gods, where he positively denied their existence (see Giannantoni 1990, IV H 14-24). This was enough reason to be banished from Athens. For further data on Theodorus and his philosophical tenets, see Long (below), 636-639.
[2] The founder of Stoicism: see alphaiota 4420, zeta 78, zeta 79.
[3] Bryson of Heraclea, a Sophist of the early 4th century BCE. He was criticized by Aristotle for an allegedly fallacious quadrature of the circle (An.Post. 75b4; Soph.El. 171b16, 172a3). In Physics 185a14-17 Aristotle also stresses that it is the geometer’s concern to refute the quadrature by means of lunes, but not as Antiphon had. 'The circle’s quadrature' is the attempt 'to measure' a circle by means of the inscription of a polygon in a circumference. Antiphon’s method apparently consisted in inscribing polygons with an increasing number of sides. He seems to have thought that, in increasing indefinitely the number of sides, the circumference of the polygon might coincide with the circle’s circumference (see Simplicius, In Phys. 54, 12ff.= DK B13 and Heat [below], 221ff.). Both Bryson’s and Antiphon’s attempts are regarded as 'eristic' and not geometrical by Aristotle.
[4] Pyrrhon of Elis (c.365–275), the founder of Greek Skepticism, called 'the Ephectic' or 'practitioner of suspended judgement'. Sextus reports that the Skeptical persuasion is 'suspensive' (e)fektikh/) from the affective state (pa/qos) that is produced in the inquirer after the investigation (see Sextus Empiricus, PH 1.7; 2.9; see also pi 3241, note 2). He studied under Bryson’s direction (though it is not sure which) and with the Democritean Anaxarchus, with whom he traveled to India. There he met the gymnosophists and magi who appear to have influenced his philosophical doctrines. Pyrrho wrote nothing, although some of his basic thoughts can be reconstructed from the fragments of his disciple Timon of Phlius (320-230) and from the Skeptic philosopher Sextus Empiricus. On Pyrrho’s philosophical viewpoints see Bett (below).
[5] For the Theodorean school and way of life see alphaiota 286, n.9, and Diogenes Laertius 2.98.
[6] Crates of Thebes (368–288), Cynic philosopher (kappa 2341). When young he became a disciple of Diogenes the Cynic (412-324; on his philosophical positions see Diogenes Laertius 6.70-73), and expressed his detachment from wealth by throwing his money into the sea. He, like his teacher Diogenes, professed cosmopolitanism and followed his mentor’s prescriptions regarding free and public sex in his relations with Hipparchia (iota 517, and see also eta 448). He was a teacher of Zeno of Citium (see note above). Stoicism. On Crates and Cynicism see Long (below) 629-632.
[7] Diogenes Laertius 6.98. The core of the quotation -- actually a question ('is this...?') -- is Euripides, Bacchae 1236.