想起來出國前在《讀者文摘》上看到的一個笑話
一位天文學家、物理學家以及一位數學家去蘇格蘭渡假，坐在火車上，他們發現窗外田野中間有一頭黑色的羊。
「多麼有趣呀！」天文學家發現並說道，「所有蘇格蘭的羊都是黑色的！」
這時，物理學家回答道：「不！是一些蘇格蘭的羊是黑色的。」
數學家懇切地凝視著天空，吟誦地唱道：「在蘇格蘭，至少存在一個田野，這個田野裡至少存在一隻羊，這隻羊至少有一麵是黑的！」
An astronomer, a physicist and a mathematician (it is said) were holidaying in Scotland. Glancing from a train window, they observed a black sheep in the middle of a field.
"How interesting," observed the astronomer, "all Scottish sheep are black!"
To which the physicist responded, "No, no! Some Scottish sheep are black!"
The mathematician gazed heavenward in supplication, and then intoned, "In Scotland there exists at least one field, containing at least one sheep, at least one side of which is black."
