Why did Aristotle reject the universal idea of the good and what does he mean by the concept free will?

They insist, rather, that free will means that man must be the "ultimate" or "originating" cause of his actions.

Explanation:

if the hares very faster than they are now, and thus the lynx's hunting success rate drops because it will be harder to catch them, the rate that will change will be the pray-rate. the pray-rate will change because more hares will be able to survive, thus more individuals for reproduction, so the end result will be increasing population of hares.

the predator-rate will remain pretty much the same because there will be more than enough pray, but the hunting success rate is stagnant.