Collinsmum, I think this idea is a very, very powerful tool in the struggle against perfectionism. If you aren't making mistakes, you aren't learning anything, and you aren't doing the right work. Very concise statement of an important principle. I have tried to teach this to my kids, because I know that it wasn't until I was much older that I grasped this, and I think my early life would have a been a much more enjoyable place for me to hang out if I had seen it when I was younger.