Few men, I imagine, who become great started on their career with the intention of becoming so. The intention generally accompanies the unsuccessful. The secret of real greatness seems to be a happy knack of doing things as they come in your way; and they rarely present themselves in the form which careful preparation would enable you to deal with.
[A good teacher] brings knowledge and his pupil into a vital relationship; and the object of teaching is to establish that relationship on an intelligible basis. This can only be done ... by appealing to two qualities which are at the bottom of all knowledge, curiosity and observation. They are born with us, every child naturally develops them, and it is the duty of the teacher to direct them to proper ends.
No people do so much harm as those who go about doing good.