He appears to have supported Zeno vigorously as to the doctrine of ‘comprehension’; and if on this subject he was worsted for the moment by Persaeus[30], he retaliated on some Academic by asking: ‘do you see who is sitting next you?’ The Academic replied ‘I do not.’ ‘Are you blind, then,’ said Aristo; ‘where are your eyes[31]?’ Still he considered any systematic study of dialectics to be a mere waste of time; like spiders’ webs, which seem to display much skill, but are of no use[32]. With regard to physics he was openly agnostic[33]; of the nature of the gods he thought we could know nothing, not even whether the deity were animate or no[34]. Ethics alone remained; but this part of philosophy he reduced by omitting all practical precepts, as introducing the element of uncertainty[35]. In ethics proper he rejects the theory of ‘things of high degree’ (προηγμένα), observing that this term does not harmonize with the treatment of advantages as ‘indifferent,’ but comes dangerously near to calling them ‘good[36].’ Virtue, or rather knowledge, is, as he maintains, the only good; and all that lies between good and evil is alike indifferent[37]. The highest good may therefore be defined as a state of indifference (ἀδιαφορία) towards all such things[38]. Aristo was however once more in agreement with Stoic doctrine when he maintained the unity of virtue. ‘The soul,’ he said, ‘has one power only, that of reasoning; one virtue only, the knowledge of good and evil. When we need to choose the good and avoid the evil, we call this knowledge Soberness; when we need to do good and not evil, we call it Wisdom; Courage, when it is bold and cautious at the right moments; and when it gives every man his due, Justice[39].’ But in deciding his action the wise man will be bound by no theories: he can do whatever comes into his head, provided only he keep himself free from distress, fear and greed[40]. The popularity of these views was repressed by the activity of Chrysippus; in Cicero’s time they were, in cultivated society, extinct[41]. But from the numerous references to Aristo in literature it is clear that his teaching was by no means forgotten; and when there took place the revival of the Cynic tone which we see illustrated in the writings of Epictetus and M. Aurelius, Aristo is again treated with high respect[42]. [Sidenote: Eratosthenes.]