“One of the hardest things for boys to learn is that a teacher is human. One of the hardest things for a teacher to learn is not to try and tell them.”

“One if the hardest things in life to learn are which bridges to cross and which bridges to burn.”

“The hardest thing to learn in life is which bridge to cross and which to burn.”

“I'm learning to fly,
But I ain't got wings.
Coming down
Is the hardest thing.”

“That is probably the hardest thing a person can learn, as I so often find in others (and in myself as well in the past) to forgive one’s own mistakes and lapses.”

“Is it important to be right or is it important to do what’s right? That’s one of the hardest lessons to learn.”

“Maybe the hardest thing in writing is simply to tell the truth about things as we see them.”

“Friendship is the hardest thing in the world to explain. It's not something you learn in school. But if you haven't learned the meaning of friendship, you really haven't learned anything.”

“The hardest lesson for humans to learn: that organic complexity will entail organic time.”

“This is one of the hardest lessons for humans to learn. We cannot admit that things might be neither good nor evil, neither cruel nor kind, but simply callous – indifferent to all suffering, lacking all purpose.”