When I come home, my daughter will run to the door and give me a big hug, and everything that's happened that day just melts away.
If in physics there's something you don't understand, you can always hide behind the uncharted depths of nature. You can always blame God. You didn't make it so complex yourself. But if your program doesn't work, there is no one to hide behind. You cannot hide behind an obstinate nature. If it doesn't work, you've messed up.