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.