A teacher can never truly teach unless he is still learning himself. The teacher who has come to the end of his subject, who has no living traffic with his knowledge but merely repeats his lesson to his students, can only load their minds, he cannot quicken them.

Power comes not from knowledge kept but from knowledge shared.

Your most unhappy customers are your greatest source of learning.

One whose knowledge is confined to books and whose wealth is in the possession of others, can use neither his knowledge nor wealth when the need for them arises.

Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.

However many holy words you read, however many you speak, what good will they do you if you do not act on upon them?