Optical Illusions

Carl Sagan Astronomer, Astrophysicist

"Our perceptions are fallible. We sometimes see what isn't there. We are prey to optical illusions. Occasionally we hallucinate. We are error-prone."

Marcel Proust Novelist

"There are optical illusions in time as well as space."

Victor Hugo Novelist, Poet

"The straight line, a respectable optical illusion which ruins many a man."

Lord Byron Poet, Novelist

"If a man proves too clearly and convincingly to himself...that a tiger is an optical illusion--well, he will find out he is wrong. The tiger will himself intervene in the discussion, in a manner which will be in every sense conclusive."