But the increased power and national advancement which these events brought to the Achaeans excited the envy of the Aetolians; who, besides their natural inclination to unjust and selfish aggrandisement, were inspired with the hope of breaking up the union of Achaean states, as they had before succeeded in partitioning those of Acarnania with Alexander, and had planned to do those of Achaia with Antigonus Gonatas. Instigated once more by similar expectations, they had now the assurance to enter into communication and close alliance at once with Antigonus (at that time ruling Macedonia as guardian of the young King Philip), and with Cleomenes, King of Sparta. They saw that Antigonus had undisputed possession of the throne of Macedonia, while he was an open and avowed enemy of the Achaeans owing to the surprise of the Acrocorinthus; and they supposed that if they could get the Lacedaemonians to join them in their hostility to the league, they would easily subdue it, by selecting a favourable opportunity for their attack, and securing that it should be assaulted on all sides at once. And they would in all probability have succeeded, but that they had left out the most important element in the calculation, namely, that in Aratus they had to reckon with an opponent to their plans of ability equal to almost any emergency. Accordingly, when they attempted this violent and unjust interference in Achaia, so far from succeeding in any of their devices, they, on the contrary, strengthened Aratus, the then president of the league, as well as the league itself. So consummate was the ability with which he foiled their plan and reduced them to impotence. The manner in which this was done will be made clear in what I am about to relate.