Happiness is like spring, according to Aristotle: just as one swallow or one day does not make a spring, one day or a short time does not make us blessed or happy. The reason is that we need a “complete life” – in Greek: zôê teleia or bios teleios. Although it is unclear how we are to define these terms, it is evident that it takes a long time before a life reaches completeness. This unclarity gives rise to several puzzles: what sort of life did Aristotle have in mind? Why is time so important? And, if we indeed need to live long before we can be happy, then how long is enough? If one day is insufficient, then how many days do we need?

My PhD thesis provides an answer to these questions, and it does so by developing a theory about what “the perfect length of life” is for Aristotelian happiness. Three ideas are central to the theory. First, I argue that Aristotle did not fully endorse Solon’s dictum, which urges us to call no living person happy. Instead, I propose that life becomes complete by reaching an aim within a lifetime, both according to the Eudemian Ethics and Nicomachean Ethics. Second, I offer a new account of the aim that must be reached: in the former text, it is “the finest measure” (ho horos kallistos) of natural goods that makes life complete; whereas in the latter work, it is the virtuous use of external goods, resulting in “great and fine” (megaloi kai kaloi) deeds. Finally, I use Aristotle’s discussion of Solon’s dictum in the Nicomachean Ethics to draw a line between being “happy” (eudaimôn) and “blessed” (makarios). While happiness is a complete activity occurring within a lifetime, blessedness means rising to the level of happiness and staying there until death. Blessedness can thus only be predicated of a whole lifespan, similarly to how Solon viewed happiness as reflecting a lifetime. Ultimately, the distinction leads to different answers to the question of the perfect length of life, depending on whether our measure is happiness or blessedness.