"To deny the evidence of one's own eyes, and to prefer to believe a doctrine which is contrary to all experience, shows a mind that is either very dull or very prejudiced."

"I cannot but be astonished that Sarsi should persist in trying to prove by means of witnesses something that I may see for myself at any time by means of experiment. Witnesses are examined in doubtful…"

"To apply oneself to a search for the truth, without any intent to serve some predetermined end, is the true path to discovery."

"It is surely harmful to souls to make it a heresy to believe what has been proved."

"Measure what is measurable, and make measurable what is not so."