One morning, having some hours to bide in a city somewhere, I was walking aimlessly along the streets and alleys when I saw a very flat ex-mouse lying flat on the pavement, so flat that it could have been its own picture. So its lungs for instance were very flat, and its heart and brains and veins and feet and belly, being in its entirety even more compact than mice are naturally disposed to be. It would have stood up and walked, I thought, but it didn’t want to upset the third dimension.