There are no doubt some who may object to our admitting to happiness living beings other than man. They might even point out that on this basis happiness could not be refused to even the lowest beings, such as plants: for they also live, their life also has a purpose, by which they seek to fulfil their development. However, it would seem rather unreasonable to say, that living beings other than humans cannot possess happiness by this mere reason that to us they seem pitiable. Besides, it would be quite possible to deny to plants what may be predicated of other living beings, on the grounds that plants lack emotion. Some might hold they are capable of happiness, on the strength of their possessing life, for a being that lives can live well or badly; and in this way we could say that they possess or lack well-being, and bear, or do not bear fruits. If (as Aristippus thought), pleasure is the goal of man, and if to live well is constituted by enjoying it, it would be absurd to claim that no living beings other than man could live well. The same argument applies if we define happiness as (a state of imperturbable tranquility, by Epicurus called) ataraxy;[2] or as (the Stoic ideal,[3] of) living conformably to nature. LIVING WELL NEED NOT BE EXTENDED EVEN TO ALL ANIMALS. 2. Those who deny the privilege of living well to plants, because these lack sensation, are not on that account obliged to grant it to all animals. For, if sensation consist in the knowledge of the experienced affection, this affection must already be good before the occurrence of the knowledge. For instance, the being must be in a state conformable to nature even though ignorant thereof. He must fulfil his proper function even when he does not know it. He must possess pleasure before perceiving it. Thus if, by the possession of this pleasure, the being already possesses the Good, he thereby possesses even well-being. What need then is there to join thereto sensation, unless indeed well-being be defined as sensation and knowledge (of an affection or state of the soul) rather than in the latter affection and state of the soul itself? EVEN THEY WHO DEFINE HAPPINESS AS SENSATION SEEK HIGHER HAPPINESS.