My mind is so clear and harmonious.

Clarity arrives in transit more than at desks. Walking to the postbox, standing on a platform, three minutes into the washing up — the thought that wouldn't come all morning turns up once you stop chasing it.

Illness and worry both crowd the room.

Anyone who has tried to think through a fever knows the mind can be borrowed from you for a while and handed back later.

It does get handed back. The clear stretches are shorter than we would like and more frequent than we notice, and the usual way to get one is to leave the house rather than to concentrate harder.