I remember while I was a kid, my father pointed me to a conundrum. In a front of our house there was a rectangle made of paths, and often we needed to cross thi

I remember while I was a kid, my father pointed me to a conundrum. In a front of our house there was a rectangle made of paths, and often we needed to cross this rectangle diagonally, but naturally we walked by its sides. And somehow we chose one path when coming home and another when moving from home. Why one path seems shorter when walking one direction and longer when walking the other one? I was grown enough to see that it is just plain stupid: both paths are of equal length. But at the same time one seemed shorter, and which one depended on a direction. He proposed a solution: we choose "more pointed" path, so we move a long side of rectangle first and a shorter one then. It is funny to see how scientists come to the same conclusion 30 years after my father.