Now that the world is reopening once more and filling with real faces, not hidden behind masks or on screens, we hold their gaze for slightly longer, perhaps because eye contact feels like a new privilege. We are aware of how quickly the world can change.

When people are conversing online, they have a phrase: "I see you." At its essence, it means "I notice your existence." Now that we can see each other again, we realise how we have missed being "seen."

We recognise people's faces instantly and without effort. We can recognise someone we know from a childhood photo. Although no one knows how this skill works, it seems to involve making a rough calculation about how the face fits together as a whole rather than comparing individual elements.