Virtue consists, not in abstaining from vice, but in not desiring it.
Some men see things as they are and ask why. Others dream of things that never were and ask why not.
The power of accurate observation is frequently called cynicism by those who have not got it.
Progress is impossible without change, and those who cannot change their minds cannot change anything.
A life spent making mistakes is not only more honourable, but more useful than a life spent doing nothing.