The squirrel was demonstrating how to build up all logic gates just from NAND but the visiting pair of jackdaws wanted to move on and discuss Shelah’s classification of countable first-order theories. We did that for long enough (35 seconds) to see that none of us had any idea what we were talking about. The husband jackdaw noted that darkness was approaching and the wife jackdaw pointed out that negations, such as darkness, can’t ‘approach’ or in fact ‘do’ anything. I was wishing we had met outside instead of in my study, birds not being noted for being continent. The squirrel sensed my concern and asked, ‘Is that the cat behind the sofa?’ Both jackdaws flew out the window but they will be back at first light …