Galileo Galilei

"A person is never too old to learn, and a mind never too wise to question."

"The mistakes and uncontrolled passions of our youth often prepare our virtues."

"They knew that it is the nature of reasoning to require examinations of any existing idea."

"If I have seen further than others, it is by standing upon the shoulders of giants."

"It is impossible for a man to be made holy by the work of his own hands."

"Philosophy is written in this grand book, the universe, which stands continually open to our gaze."

"The human understanding is no dry light, but receives an infusion from the will and affections."

"Fear is the prison of the heart."

"Do you know what astonishes me the most in this world? The inability of force to create anything lasting."

"Infinite worlds, infinite possibilities - yet we understand so little."

"The diurnal rotation of the earth is the most marvelous phenomenon of nature."

"I think that tastes are made, not born."

"Slow and steady observation defeats hasty assumption."

"Mathematics is the language with which God has written the universe."

"To be afraid is the condition of being a man."

"The test of knowledge is experiment."

"Justice is the first virtue of those who command, and stops, or ought to stop, at the threshold where force begins."

"We are all philosophers, though few know themselves to be so."

"Perseverance and passion are the keys that unlock all doors."

"Life is what happens when you are busy making calculations."

"The greatest enemy of knowledge is not ignorance, but the illusion of knowledge."

"I have discovered things so wonderful that my tongue fails me, and in envy I curse all booked learning."

"Small room, dark room, but from which can be seen the stars."

"Sunspots are not illusions of the telescope but facts of nature."

"Contradiction is the bellwether of hidden truth."

"The greatest truths are the simplest things in the world, simple as your own breath."

"Authority without knowledge is tyranny."

"Nature uses only the longest threads to weave her patterns."

"Art is the task of living with beauty."

"Confusion of cause and effect is at the root of all philosophical error."