Nothing that makes us happy is an illusion.

The line comes from Goethe’s epistolary novel "The Sorrows of Young Werther". In a letter dated July 18, Werther describes how merely seeing a servant who has been in Charlotte’s presence makes him feel unusually happy, and he asks his friend Wilhelm whether something that produces such happiness can really be dismissed as mere illusion.

The remark defends emotionally meaningful experiences against being written off as unreal or worthless. Even if the feeling is based on longing or imagination, Werther argues that the happiness it creates gives it a kind of validity.

Nothing which makes us happy is an illusion.

Can that be a delusion which makes us happy?