The only cow in a small town in Poland stopped giving milk. The people did some research and found that they could buy a cow from Moscow for 2,000 rubles, or one from Minsk for 1,000 rubles.

Being frugal, they bought the cow from Minsk. The cow was wonderful.  It produced lots of milk all the time, and the people were amazed and very happy. 

They decided to acquire a bull to mate with the cow and produce more cows like it.  Then they would never have to worry about the milk supply again. 

They bought a bull and put it in the pasture with their beloved cow.  However, whenever the bull came close to the cow, the cow would move away. No matter what approach the bull tried, the cow would move away from the bull and the amorous bull could not succeed in his quest. 

The people were very upset and decided to ask the rabbi, who was very wise, what to do.  They told the rabbi what was happening.  "Whenever the bull approaches our cow, she moves away.  If he approaches from the back, she moves forward.  When he approaches her from the front, she backs off.  An approach from the side and she just walks away to the other side." 

The rabbi thought about this for a minute and then asked; "Did you buy this cow from Minsk?"

The people were dumbfounded, since they had never mentioned where they had gotten the cow. 

"You are truly a wise rabbi," they said.  "How did you know we got the cow from Minsk?"

The rabbi answered; "My wife is from Minsk.”