He knows that pain through his own experience.

She described the pain of a broken heart as tears.

He emphasized his belief by saying, 'I believe in order to understand.'

I don't know a thing about him.

This ancient proverb, 'know the other side and yourself, and you will not be in danger in a hundred battles', teaches us the importance of understanding ourselves and others.

He is the type of person who understands ten from hearing one.

He spoke of his big dreams, saying, 'How can a sparrow understand the ambitions of a swan?'

He is exactly in the state of 'A frog in a well does not know the vast ocean.'