Galileo Galilei

"I have discovered four new planets."

"We must not pretend to possess more knowledge than we actually do."

"The mind, once expanded by a new experience, never returns to its original dimensions."

"One cannot teach what one does not know."

"The heavens declare the glory of God, and mathematics declares the mind of God."

"I do not agree with those who believe that truth is established by arguments and authorities."

"Physics is really nothing more than a search for ultimate simplicity, but so far all we have is a kind of elegant messiness."

"All things are in flux; nothing is permanent but change itself."

"In my studies of astronomy and philosophy, I have always found that facts, unaided by rhetoric, persuade men."

"The laws of nature are written by God in the language of mathematics."

"To arrive at truth, one must first doubt accepted knowledge."

"I heard once that the sun was round, yet all the mighty men of Earth still viewed it as a point of light in the sky."

"Wisdom begins in wonder."

"The book of nature cannot be read until we have learned the language and become familiar with the characters in which it is written."

"You cannot lead men on a path without showing them where it leads."

"Errors are not vices of mankind but fruits through which mankind may grow."

"It were well if people spent less time proving their knowledge and more time acquiring it."

"In my observations of the heavens, I found that the eye deceives, but the telescope does not."

"The sun teaches to us that the center of all life is burning, all-consuming, and eternal."

"I resolved to distinguish the true from the false as early as possible in my studies."

"One of the greatest human gifts is the power to question."

"If you could have a sign of your wisdom, let it be that you know when to doubt."

"Authority is not a substitute for the facts."

"Progress comes from improving the tools by which we understand."

"The universe is an enormous and intricate design one must approach with both care and wonder."

"He who would teach must first prove his understanding through observation and reason."

"Do not believe anything unless you can prove it through observation and reason."

"The endeavor to understand the universe is one of the very few things that lifts human life a little above the level of farce."

"I am certain that those who believe God has made the universe perfect are right."

"Our eyes see the truth if we allow them to look without prejudice."