When I was young, I found that I could pick up mathematics very easily, and I simply couldn't understand why other people bitched and moaned about it so much. After all, it was a really easy skill that anybody could learn if they just tried.

It wasn't until many years later that I fully grokked that other people pick up certain skills at different rates to me. That what s so obvious and easy for me, might not be obvious and easy for another person. and vice versa.

I now try very hard not to assume that something is easy to learn... and therefore also try not to assume that somebody has also actually learned something that I have learned.

I mess up on that too - all the time. But I feel that it's good to keep in mind when you can.