Friends have suggested that I am the least qualified person to talk about happiness, because I am often down, and sometimes profoundly depressed. But I think that’s where my qualification comes from. Because to know happiness, it helps to know unhappiness.

Campbell frames lived experience of depression not as a disqualification but as a form of authority: someone who has known profound lows can speak credibly about what happiness is and what it is not. The quote suggests happiness is relational and contrastive—felt more clearly against the memory of unhappiness—rather than a constant mood or permanent achievement. It also pushes back against stigma by treating depression as a source of insight rather than shame. Implicitly, Campbell argues for a more realistic, hard-won account of wellbeing: happiness is not the absence of suffering, but something understood, valued, and pursued with an awareness of vulnerability.