 The extent of Numenius' influence on Plotinus was debated in antiquity. Plotinus' students, Amelius and Porphyry, were concerned to discredit the widespread charge of Plotinus' plagiarism of Numenius (Life of Plotinus 18.1–8, 21.1–9).  Amelius, who is attested to have known Numenius' work by heart (ibid. 3.44–5), devoted a special work on this topic, On the Difference Between the Doctrines of Plotinus and Those of Numenius (ibid. 17.1–6).  Porphyry discusses the matter extensively in his biography of Plotinus (ibid. 17–18, 21.1–9), making reference to Amelius' work mentioned above as well as to Longinus' claim that Plotinus' works were far superior in terms of precision to Numenius', Cronius', Moderatus', and Thrasyllus' (ibid.  20.71–76, 21.5–9). Clearly, however, several of Plotinus' views resemble those of Numenius: both distinguish three intelligible principles, both consider matter to be evil, although Plotinus does not raise it into a principle (see Ennead I.8), and both consider the soul to be essentially an intellect.