Quote by Wilhelm Johannsen

"Genetics is the science of heredity, and heredity is the fundamental principle of life."

"The gene is the unit of heredity, but it is not the unit of evolution."

"Nature does nothing suddenly, and gradualism is the law of change."

"Pure lines are the foundation of scientific breeding."

"Perseverance is the key to success."

"Don't give up on what you believe in."

"I've been through worse."

"You learn to live with the pain."