Now in all Aristotle’s works there is not a single sentence in praise of Alexander and there is some evidence that the two had become estranged. In support of this we may quote Plutarch (_c._ A. D. 100) who gives a detailed description of a conspiracy in 327 B. C. against Alexander by Callisthenes, a pupil of Aristotle who appears to have kept up a correspondence with his master.[17] Alexander himself wrote of Callisthenes, according to Plutarch: ‘I will punish this sophist, together with those who sent him to me and those who harbour in their cities men who conspire against my life’ and Plutarch adds that Alexander ‘directly reveals in these words a hostility to Aristotle in whose house Callisthenes ... had been reared, being a son of Hero who was a niece of Aristotle’.[18] Yet the Alexandrian conquests, bringing Greece into closer contact with a wider world and extending Greek knowledge of the Orient, must have had their influence in stimulating interest in rare and curious creatures and in a general extension of natural knowledge. That the interest in these topics extended beyond the circle of the Peripatetics is shown by the fact that Speusippus, the pupil of Plato and his successor as leader of his school, occupied himself with natural history and wrote works on biological topics and especially on fish. [17] The statement of the relation of Callisthenes to Aristotle rests on the somewhat unsatisfactory evidence of Simplicius (sixth century) who states that Callisthenes sent Aristotle certain astronomical observations from Babylon. Simplicius, _Commentarii_ (Karsten), p. 226. [18] Plutarch, _Alexander_, lv. Nevertheless, remarkable as is Aristotle’s acquaintance with animal forms, investigation shows that he is reliable only when treating of creatures native to the Aegean basin. As soon as he gets outside that area his statements are almost always founded on hearsay or even on fable.[19] Whatever assistance Aristotle may have received in the preparation of his biological works came, therefore, probably from no such picturesque and distant source as the gossip of Pliny or Aelian would suggest. We can conjecture that he received aid from the powerful relatives of his wife at Atarneus and in Lesbos, and we may most reasonably suppose that after his return to Athens much help would have been given him by his pupils within the Lyceum. To them may probably be ascribed many passages in the biological writings; for it seems hardly possible that Aristotle himself would have had time for detailed biological research after he had settled as a teacher in Athens. Of the work of these members of his school a fine monument has survived in two complete botanical treatises and fragments of others on zoological and psychological subjects by Theophrastus of Eresus, his pupil and successor in the leadership of the Lyceum and perhaps his literary legatee.