Our greatest weakness lies in giving up. The most certain way to succeed is always to try just one more time.

More from Thomas Edison

• Genius is one per cent inspiration, ninety-nine per cent perspiration.
• Many of life's failures are people who didn't realize how close they were to success when they gave up.
• I have not failed. I've just found 10,000 ways that won't work.
• Opportunity is missed by most people because it is dressed in overalls and looks like work.
• Aim above morality. Be not simply good; be good for something.
• A journey of a thousand miles begins with a single step.