A quick note on where this comes from, since it's often shared as a personal Hemingway maxim: he did write it, but it's spoken by a character named Marita, in his novel The Garden of Eden, published posthumously in 1986. It's dialogue, not a diary entry — though given how closely Hemingway's own life tracked the idea, the distinction may matter less than it first appears.

The observation itself cuts close to the bone. Why would intelligence make happiness harder, not easier? The uncomfortable answer the line points toward is that a sharp, restless mind is built to notice — flaws, risks, contradictions, the gap between how things are and how they could be. That noticing is often exactly what makes someone intelligent in the first place. But happiness frequently depends on the opposite skill: the ability to let some things simply be, without endlessly interrogating them, to rest in a moment rather than picking it apart.

Hemingway himself is a striking, sobering case study for the line, whoever technically speaks it in the novel. He lived a famously restless, hard-driving life — wars, marriages, fame, physical injury, and a struggle with depression that ended in his own death in 1961. A brilliant, perceptive mind, by nearly any account, and one that plainly found sustained happiness elusive. The line reads less like idle cleverness and more like something earned through direct, difficult experience.

It's not a reason to distrust your own intelligence, but it is a useful warning about one of its common side effects: the tendency to over-examine a good moment until the examining itself crowds out the good. If you recognize that pattern in yourself, the corrective isn't to think less, but to notice when thinking has started working against you — and to practise, deliberately, the harder skill of simply letting a happy moment be one, at least for a little while.