“He who acquires knowledge and acts up to it and teaches it to the people is noble to the angels of heaven and earth. He is like the sun which illumines itself and gives light to other things. Such a man is like a pot of musk which is full of fragrance and gives fragrance to others. He who teaches knowledge to others but does not himself act up to it is like a notebook which does not benefit itself but benefits others or like an instrument which gives edge to iron but itself has got no edge, or like a needle which remains naked but sews clothing for others, or like a lamp which gives light to other things but itself burns.”