(2) No lunatics are fit to serve on a jury;
(3) None of your sons can do Logic.
The Universal was "persons". The symbols were: a—able to do Logic; b—fit to serve on a jury; c—sane; d—your sons.
And the answer, of course, was: None of your sons is fit to serve on a jury.
For some reason this, in turn, made him think of the ancient conundrum that employed confusion to trip its victims: What's the difference between an iron dog in the side yard of a man who wants to give his little daughter music lessons but is afraid he can't afford them next year, and a man who has a whale in a tank and wants to send him for a wedding present and is trying to pin a tag on him, saying how long he is, how much he weighs and where he comes from, but can't because the whale keeps sloshing around in the tank and knocking the tag off?
This time, the answer was: One can't wag his tail, the other can't tag his whale.
"None of your sons is fit to tag a whale—or wag a tail," he said absently.
"What was that?" Nina asked.
"Nothing, nothing at all," he replied. "Merely a man going out of his mind."
"It will never miss you," she replied brightly. But her brightness became a bit strained as the day wore on. The trip, for Lindsay, was sheer nightmare. No sane man can wag his tail, he kept thinking.