3. Now if we draw no distinction as to kinds of life, everything that lives will be capable of happiness, and those will be effectively happy who possess that one common gift of which every living thing is by nature receptive. We could not deny it to the irrational whilst allowing it to the rational. If happiness were inherent in the bare being-alive, the common ground in which the cause of happiness could always take root would be simply life.
Those, then, that set happiness not in the mere living but in the reasoning life seem to overlook the fact that they are not really making it depend upon life at all: they admit that this reasoning faculty, round which they centre happiness, is a property [not the subject of a property]: the subject, to them, must be the Reasoning-Life since it is in this double term that they find the basis of the happiness: so that they are making it consist not in life but in a particular kind of life- not, of course, a species formally opposite but, in terminology, standing as an "earlier" to a "later" in the one Kind.
Now in common use this word "Life" embraces many forms which shade down from primal to secondary and so on, all massed under the common term- life of plant and life of animal- each phase brighter or dimmer than its next: and so it evidently must be with the Good-of-Life. And if thing is ever the image of thing, so every Good must always be the image of a higher Good.
If mere Being is insufficient, if happiness demands fulness of life, and exists, therefore, where nothing is lacking of all that belongs to the idea of life, then happiness can exist only in a being that lives fully.
And such a one will possess not merely the good, but the Supreme Good if, that is to say, in the realm of existents the Supreme Good can be no other than the authentically living, no other than Life in its greatest plenitude, life in which the good is present as something essential not as something brought from without, a life needing no foreign substance called in from a foreign realm, to establish it in good.
For what could be added to the fullest life to make it the best life? If anyone should answer, "The nature of Good" [The Good, as a Divine Hypostasis], the reply would certainly be near our thought, but we are not seeking the Cause but the main constituent.
It has been said more than once that the perfect life and the true life, the essential life, is in the Intellectual Nature beyond this sphere, and that all other forms of life are incomplete, are phantoms of life, imperfect, not pure, not more truly life than they are its contrary: here let it be said succinctly that since all living things proceed from the one principle but possess life in different degrees, this principle must be the first life and the most complete.