"As a philosopher, his first great characteristic was the trust which he put in facts. He said of himself, "In early life I was a very lively imaginative person, who could believe in the Arabian Nights as easily as in the Encyclopedia, but facts were important to me, and saved me. I could trust a fact." Over and over again he showed his love of experiments in his writings and lectures: "Without experiment I am nothing." "But still try, for who knows what is possible?" "All our theories are fixed upon uncertain data, and all of them want alteration and support from facts." "One thing, however, is fortunate, which is, that whatever our opinions, they do not alter nor derange the laws of nature." His second great characteristic was his imagination. It rose sometimes to divination, or scientific second sight, and led him to anticipate results that he or others afterwards proved to be true."