“…Knowing who…

“…Knowing who I actually am is the key to reach perfection… Because that means knowing what I can and cannot do.”
“That’s what a loser would say. Isn’t acknowledging what you can’t do the same as giving up?”
“No. It means… to forgive yourself for what you aren’t able to do.”

An exchange between Itachi and Kabuto during their fight. Definitely a good take on the moral of knowing your limits.