"Our minds are seldom without a range of moods, a kind of emotional weather, that scud over our mental horizons, normally without us having any understanding of where they have come from, when they might lift or even that they exist. 

However, these moods can have a decisive impact on the gestation of our ideas. We might in one mood consider ourselves fortunate, look brightly at the future and feel grateful to those around us. And then, a few hours later, without anything in the outer world having changed, another mood might lead us to a wholesale re-evaluation of almost everything about us. 

Devilishly, part of what it means to be subject to a mood is not to realise that we are in its grip".

Emotional scepticism.