Chronological Chart of Sources for Pythagoras

Post-Aristotelian Sources for Pythagoras
The problems regarding the sources for the life and philosophy of Pythagoras are quite complicated, but it is impossible to understand the Pythagorean Question without an accurate appreciation of at least the general nature of these problems. It is best to start with the extensive but problematic later evidence and work back to the earlier reliable evidence. The most detailed, extended and hence most influential accounts of Pythagoras' life and thought date to the third century CE, some 800 years after he died. Diogenes Laertius (ca. 200–250 CE) and Porphyry (ca. 234–305 CE) each wrote a Life of Pythagoras, while Iamblichus (ca. 245–325 CE) wrote On the Pythagorean Life, which includes some biography but focuses more on the way of life established by Pythagoras for his followers. All of these works were written at a time when Pythagoras' achievements had become considerably exaggerated. Diogenes may have some claim to objectivity, but both Iamblichus and Porphyry have strong agendas that have little to do with historical accuracy. Iamblichus presents Pythagoras as a soul sent from the gods to enlighten mankind (O'Meara 1989, 35–40). Iamblichus' work was just the first in a ten volume work, which in effect Pythagoreanized Neoplatonism, but the Pythagoreanism involved was Iamblichus' own conception of Pythagoras as particularly concerned with mathematics rather than an account of Pythagoreanism based on the earliest evidence. Porphyry also emphasizes Pythagoras' divine aspects and may be setting him up as a rival to Jesus (Iamblichus 1991, 14). These three third-century accounts of Pythagoras were in turn based on earlier sources, which are now lost. Some of these earlier sources were heavily contaminated by the Neopythagorean view of Pythagoras as the source of all true philosophy, whose ideas Plato, Aristotle and all later Greek philosophers plagiarized. Iamblichus cites both Nicomachus of Gerasa's and Apollonius of Tyana's biographies of Pythagoras (VP 251 and 254) and appears to have used them extensively even where they are not cited (Burkert 1972a, 98 ff.). Nicomachus (ca. 50 – ca. 150 CE) assigns Pythagoras a metaphysics that is patently Platonic and Aristotelian and that employs distinctive Platonic and Aristotelian terminology (Introduction to Arithmetic I.1), while Apollonius (1st CE) venerated Pythagoras as the model for his ascetic life. Porphyry (VP 48–53) explicitly cites Moderatus of Gades as one of his sources. Moderatus was an “agressive” Neopythagorean of the first century CE, who reports that Plato, Aristotle, and their pupils Speusippus, Aristoxenus and Xenocrates took for their own everything that was fruitful in Pythagoreanism, leaving only what was superficial and trivial to be ascribed to the school (Dillon 1977, 346). Diogenes Laertius, who appears to have less personal allegiance to the Pythagorean legend, bases his primary account of Pythagoras' philosophy (VIII. 24–33) on the Pythagorean Memoirs excerpted by Alexander Polyhistor, which are a forgery dating sometime around 200 BCE and which assign not just Platonic but also Stoic ideas to Pythagoras (Burkert 1972a, 53; Kahn 2001, 79–83).
In the Pythagorean Memoirs, Pythagoras is said to have adopted the Monad and the Indefinite Dyad as incorporeal principles, from which arise first the numbers, then plane and solid figures and finally the bodies of the sensible world (Diogenes Laertius VIII. 25). This is the philosophical system that is most commonly ascribed to Pythagoras in the post-Aristotelian tradition, and it is found in Sextus Empiricus' (2nd century CE) detailed accounts of Pythagoreanism (e.g., M. X. 261) and most significantly in the influential handbook of the differing opinions of the Greek philosophers, which was compiled by Aetius in the first century CE and goes back to Aristotle's pupil Theophrastus (e.g., H. Diels, Doxographi Graeci I. 3.8). The testimony of Aristotle makes completely clear, however, that this was the philosophical system of Plato in his later years and not that of Pythagoras or even the later Pythagoreans. Aristotle is explicit that the indefinite dyad is unique to Plato (Metaphysics 987b26 ff.) and that the Pythagoreans recognized only the sensible world and hence did not derive it from immaterial principles. Although Theophrastus usually follows his teacher Aristotle quite closely in his reports of the views of the early Greek philosophers, in this case he appears to agree with the later tradition in ascribing late Platonic metaphysics to Pythagoras. How are we to explain this divergence from the Aristotelian view? It appears that, for reasons which are not entirely clear, Plato's successors in the Academy, Speusippus, Xenocrates and Heraclides, chose to present late Platonic metaphysics as a mere development of Pythagoreanism and that Theophrastus chose to follow this tradition. In the Philebus, Plato himself, while acknowledging a debt to the philosophy of limiters and unlimiteds, which is found in Aristotle's accounts of Pythagoreanism and in the fragments of the fifth-century Pythagorean Philolaus, makes clear that this is a considerably earlier philosophy, which he is completely reworking for his own purposes (16c ff.; see Huffman 1999a and 2001). The crucial and striking point is that the tradition which falsely ascribes Plato's late metaphysics to Pythagoras begins not with the Neopythagoreans in the first centuries BCE and CE but already in the fourth century BCE among Plato's own pupils (Burkert 1972a, 53–83; Dillon 2003, 61–62 and 153–154). Aristotle's careful distinctions between Plato and fifth-century Pythagoreanism, which make excellent sense in terms of the general development of Greek philosophy, are largely ignored in the later tradition in favor of the more sensational ascription of mature Platonism to Pythagoras.
If we step back for a minute and compare the sources for Pythagoras with those available for other early Greek philosophers, the extent of the difficulties inherent in the Pythagorean Question becomes clear. When trying to reconstruct the philosophy of Heraclitus, for example, modern scholars rely above all on the actual quotations from Heraclitus' book preserved in later authors. Since Pythagoras wrote no books, this most fundamental of all sources is denied us. In dealing with Heraclitus, the modern scholar turns with reluctance next to the doxographical tradition, the tradition represented by Aetius in the first century CE, which preserves in handbook form a systematic account of the beliefs of the Greek philosophers on a series of topics having to do with the physical world and its first principles. Aetius' work has been reconstructed by Hermann Diels on the basis of two later works, which were derived from it, the Selections of Stobaeus (5th century CE) and the Opinions of Philosophers by pseudo-Plutarch (2nd century CE). Scholars' faith in this evidence is largely based on the assumption that most of it goes back to Aristotle's school and in particular to Theophrastus' Tenets of the Natural Philosophers. Here again the case of Pythagoras is exceptional. Pythagoras is represented in this tradition but, as we have seen, Theophrastus in this case adopted the view of Pythagoras promulgated by Plato's successors in the early Academy, a view that, against all historical plausibility, assigns Plato's later metaphysics to Pythagoras. This is a view which is explicitly rejected by Theophrastus' teacher Aristotle. Thus, the second standard source for evidence for early Greek philosophy is, in the case of Pythagoras, tainted at the source. Whatever views Pythagoras might have had are replaced by late Platonic metaphysics in the doxographical tradition.
A third source of evidence for early Greek philosophy is regarded with great skepticism by most scholars and, in the case of most early Greek philosophers, used only with great caution. This is the biographical tradition represented by the Lives of the Philosophers written by Diogenes Laertius. In this case we at first sight appear to be in luck, at least with regard to the amount of evidence for Pythagoras, since, as we have seen, two major accounts of the life of Pythagoras and the Pythagorean way of life survive in addition to Diogenes' life. Unfortunately, these two additional lives are written by authors (Iamblichus and Porphyry) whose goal is explicitly non-historical, and all three of the lives rely heavily on authors in the Neopythagorean tradition, whose goal was to show that all later Greek philosophy, insofar as it was true, had been stolen from Pythagoras. There are, however, some sections in these three lives that derive from sources that go back beyond the distorting influence of Neopythagoreanism, to sources in the fourth-century BCE, sources which are also independent of the early Academy's attempt to assign Platonic metaphysics to the Pythagoreans. The most important of these sources are the fragments of Aristotle's lost treatises on the Pythagoreans and the fragments of works on Pythagoreanism or of works which dealt in passing with Pythagoreanism written by Aristotle's pupils Dicaearchus and Aristoxenus, in the second half of the fourth century BCE. The historian Timaeus of Tauromenium (ca. 350–260 BCE), who wrote a history of Sicily, which included material on southern Italy where Pythagoras was active, is also important. In some cases, the fragments of these early works are clearly identified in the later lives, but in other cases we may suspect that they are the source of a given passage without being able to be certain. Large problems remain even in the case of these sources. They were all written 150–250 years after the death of Pythagoras; given the lack of written evidence for Pythagoras, they are based largely on oral traditions. Aristoxenus, who grew up in the southern Italian town of Tarentum, where the Pythagorean Archytas was the dominant political figure, and who was himself a Pythagorean before joining Aristotle's school, undoubtedly had a rich set of oral traditions upon which to draw. It is clear, nonetheless, that 150 years after his death conflicting traditions regarding Pythagoras' beliefs had arisen on even the most central issues. Thus, Aristoxenus is emphatic that Pythagoras was not a strict vegetarian and ate a number of types of meat (Diogenes Laertius VIII. 20), whereas Aristoxenus' contemporary, the mathematician Eudoxus, portrays him not only as avoiding all meat but as even refusing to associate with butchers (Porphyry, VP 7). Even among fourth-century authors that had at least some pretensions to historical accuracy and who had access to the best information available, there are widely divergent presentations, simply because such contradictions were endemic to the evidence available in the fourth century. What we can hope to obtain from the evidence presented by Aristotle, Aristoxenus, Dicaearchus, and Timaeus is thus not a picture of Pythagoras that is consistent in all respects but rather a picture that at least defines the main areas of his achievement. This picture can then be tested by the most fundamental evidence of all, the testimony of authors that precede even Aristotle, testimony in some cases that derives from Pythagoras' own contemporaries. This testimony is extremely limited, about twenty brief references, but this dearth of evidence is not unique to Pythagoras. The pre-Aristotelian testimony for Pythagoras is more extensive than for most other early Greek philosophers and is thus testimony to his fame.
Plato and Aristotle as Sources for Pythagoras
In reconstructing the thought of early Greek philosophers, scholars often turn to Aristotle's and Plato's accounts of their predecessors, although Plato's accounts are embedded in the literary structure of his dialogues and thus do not pretend to historical accuracy, while Aristotle's apparently more historical presentation masks a considerable amount of reinterpretation of his predecessors' views in terms of his own thought. In the case of Pythagoras, what is striking is the essential agreement of Plato and Aristotle in their presentation of his significance. Aristotle frequently discusses the philosophy of Pythagoreans, whom he dates to the middle and second half of the fifth century and who posited limiters and unlimiteds as first principles. He refers to these Pythagoreans as the “so-called Pythagoreans,” suggesting that he had some reservations about the application of the label “Pythagorean” to them. Aristotle strikingly never refers to Pythagoras himself in his extant writings (Metaph. 986a29 is an interpolation; Rh. 1398b14 is a quotation from Alcidamas; MM 1182a11 may not be by Aristotle and, if it is, may well be a case where “Pythagoreans” have been turned into “Pythagoras” in the transmission). In the fragments of his now lost two-book treatise on the Pythagoreans, Aristotle does discuss Pythagoras himself, but the references are all to Pythagoras as a founder of a way of life, who forbade the eating of beans (Fr. 195), and to Pythagoras as a wonder-worker, who had a golden thigh and bit a snake to death (Fr. 191). If this is the only type of material that Aristotle is willing to ascribe to Pythagoras himself, it becomes clear why he never mentions Pythagoras in his account of his philosophical predecessors and why he uses the expression “so-called Pythagoreans” to refer to the Pythagoreanism of the fifth-century. For Aristotle Pythagoras did not belong to the succession of thinkers starting with Thales, who were attempting to explain the basic principles of the natural world, and hence he could not see what sense it made to call a fifth-century thinker like Philolaus, who joined that succession by positing limiters and unlimiteds as first principles, a Pythagorean. Plato is often thought to be heavily indebted to the Pythagoreans, but he is almost as parsimonious in his references to Pythagoras as Aristotle and mentions him only once in his writings. Plato's one reference to Pythagoras (R. 600a) treats him as the founder of a way of life, just as Aristotle does, and, when Plato traces the history of philosophy prior to his time in the Sophist, (242c-e), there is no allusion to Pythagoras. In the Philebus, Plato does describe the philosophy of limiters and unlimiteds, which Aristotle assigns to the so-called Pythagoreans of the fifth century and which is found in the fragments of Philolaus, but like Aristotle he does not ascribe this philosophy to Pythagoras himself. Scholars, both ancient and modern, under the influence of the later glorification of Pythagoras, have supposed that the Prometheus, whom Plato describes as hurling the system down to men, was Pythagoras (e.g., Kahn 2002: 13–14), but careful reading of the passage shows that Prometheus is just Prometheus and that Plato, like Aristotle, assigns the philosophical system to a group of men (Huffman 1999a, 2001). The fragments of Philolaus show that he was the primary figure of this group. When Plato refers to Philolaus in the Phaedo (61d-e), he does not identify him as a Pythagorean, so that once again Plato agrees with Aristotle in distancing the “so-called Pythagoreans” of the fifth century from Pythagoras himself. For both Plato and Aristotle, then, Pythagoras is not a part of the cosmological and metaphysical tradition of Presocratic philosophy nor is he closely connected to the metaphysical system presented by fifth-century Pythagoreans like Philolaus; he is instead the founder of a way of life.