Finally found the full quote...

[corinath]

Nothing in the world can take the place of Persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan “Press On” has solved and always will solve the problems of the human race.
- Calvin Coolidge