When I was twenty, an architect friend-of-a-friend designed a house where kitchen and shower wastewater ran in a stream across an internal atrium, the idea being that an awareness of one’s effluvia was a prerequisite for dealing with it effectively.

At the time, I didn’t get it: I had an intellectual appreciation for environmental concerns, but I didn’t see what I do now – how intuitively right his solution was. What is it, to feel something deeply, rather than just thinking it? What’s the difference between “knowing” and knowing?