No pessimist ever discovered the secret of the stars

"No pessimist ever discovered the secret of the stars, or
sailed to an uncharted land, or opened a new doorway for the
human spirit."

-- Helen Keller

Pessimist is a negative attitude, it turns down bright ideas, it brings dark to light. While the opposite; optimist bring power and hope to achieved greater and wider horizons. It gives way to more opportunities.