Reason, observation, and experience; the holy trinity of science.
All men dream, but unequally. Those that dream at night in the dusty recesses of their minds awake the next day to find that their dreams were just vanity. But those who dream during the day with their eyes wide open are dangerous men; they act out their dreams to make them reality.
Nothing in this world can take the place of persistence. Talent will not nothing is more common than unsuccessful people with talent. Genius will not unrewarded genius is almost a proverb. Education will not the world is full of educated failures. Persistence and determination alone are omnipotent.