Men may be very learned, and yet very miserable; it is easy to be a deep geometrician, or a sublime astronomer, but very difficult to be a good man. I esteem, therefore, the traveller who instructs the heart, but despise him who only indulges the imagination. A man who leaves home to mend himself and others, is a philosopher; but he who goes from country to country, guided by the blind impulse of curiosity, is only a vagabond.