Spotting condensation on any glass, climb up next to it. Trace your finger through it, push it around. Trace your finger slowly, to feel both the soft, cold wetness of fog and the cold, brittle hardness of glass. Trace your finger with a sudden jolt, to feel the sensation of slashing without damage or harm. Draw stick figure cartoon panels. Misspell words. Design intricate visual tapestries. Run from room to room in the building and draw on as many windows as possible before the condensation fades and returns to the air. This is where you learn what’s ephemeral.