  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 biographies of Pythagoras by Nicomachus of Gerasa and a certain Apollonius (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). If the Apollonius cited by Iamblichus is Apollonius of Tyana (1st CE), his account will be influenced by his veneration of Pythagoras as the model for his ascetic life, but some scholars argue that Iamblichus is using an otherwise unknown Apollonius (Flinterman 2014, 357). Porphyry (VP 48–53) explicitly cites Moderatus of Gades as one of his sources. Moderatus was an “aggressive” 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).