Hans Eysenck

"The brain chemistry of introverts and extroverts operates on fundamentally different principles."

"Neuroticism can drive both great art and great suffering."

"We must understand ourselves first before we can truly understand others."

"The stability of personality across the lifespan is one of psychology's most robust findings."

"Behavior is the product of personality interacting with circumstance."

"Those who deny the role of genetics in personality are denying reality."

"Psychometric testing revealed patterns in human nature that introspection alone could never find."

"The best predictor of future behavior is past behavior under similar circumstances."

"Personality exists on continuums, not in categories."

"The introvert's need for solitude is not antisocial; it is self-preserving."

"We are not infinitely malleable; there are limits to what psychology can change."

"Extraversion is a style, not a superiority."

"The nervous system responds differently to stimulation based on inherited traits."

"Understanding personality type helps us forgive others for being different."

"Personality psychology is the study of why humans are wonderfully inconsistent."

"Conditioning works best in harmony with personality, not against it."

"The debate between nature and nurture is not a debate at all; it is both."

"Neuroticism is overrepresented in creative individuals, suggesting a link between emotional sensitivity and imagination."

"We must design environments that accommodate different personality types."

"The mind operates according to principles as lawful as physics, though more complex."

"Introversion in a world of extroverts requires not change, but acceptance."

"Personality traits predict outcomes better than circumstances in many domains."

"The anxious person perceives threats others ignore; this is not madness but difference."

"Behavior therapy works because it works with personality, not by ignoring it."

"Psychoticism represents nonconformity; whether it becomes creativity or criminality depends on other factors."

"We are born with our personality tendencies, but we are not born with our character."

"The extravert's sociability is not superiority; it is simply a different way of being."

"Genetic predisposition is not destiny; it is direction."

"Understanding personality type is the first step toward genuine tolerance."

"The brain's arousal system explains much of what we call personality differences."