EUDAIMONIA. (noun) from the ancient Greek εὐδαιμονία: The ideal state of human flourishing. To go beyond happiness, health, and prosperity, to living a meaningful and virtuous life.

I suspect that some of the best constraints to consider are those with a strong historical precedent: family, work, marriage, membership of clubs and groups, schedules and routines, religion, children.

Humans are pretty smart, as individuals. But in groups, we're capable of breathtaking feats of stupidity. We're going to examine some of these herd dynamics in Book II. For now, it's enough to know that there are strong cultural, social, and biological forces that conspire to make it really hard to make good trade-offs.

Luhmann's insight was that starting with a blank page and casting around for inspiration gets the creative process bass-ackwards. After years of building chains of thoughts and connected ideas, you will have more topics ricocheting around your skull and begging to be put on the page than you can possibly get to in a lifetime.

While Thoreau’s critics always seem to miss this point, he specifically urged readers not to blindly imitate his mode of living: “I desire that there may be as many different persons in the world as possible; but I would have each one be very careful to find out and pursue his own way.”

As it turns out, calisthenics is structured strength training. The clue is in the name: kallos + sthenos, from the ancient Greek for ‘beauty’ and ‘strength’. Just like weightlifting, you’re moving through space against resistance, reaping large benefits from small bursts of intense effort. The only difference is that instead of using lumps of iron

This gives us the barbell strategy for barbells: short bursts of intense effort on the hyper-aggressive ‘expensive’ end, and lots of low-effort movement on the hyper-conservative ‘cheap’ end (Fig. 3.6). The distribution is highly asymmetrical, so we might aim for 2.5 hours of intense exercise each week, but 25 hours of gentle movement.

Here's the simplest definition of optionality: Optionality = the right, but not the obligation, to take action

Law of Comparative Advantage. Even if you’re a polymath freak who can beat your competitors at every task, you still ought to maximise your gains by focusing on the one area you have the highest relative advantage, and trade in exchange for everything else. This is a highly counterintuitive insight, but it's one of the most widely-accepted ideas in