Louis Pasteur

From CONVICTIONS AND STATES OF MIND, 1927 by Cassius Jackson Keyser

States of mind are for the most part induced in us by th sentiments and faiths of the house hold, the neighborhood, and the family newspaper. We derive our states of mind from the social atmosphere by a kind of cerebral suction. But a conviction is a result of hard, patient, and honest thinking—the rarest activity of man. Honest thinking is attended by serious doubt. "In experimental science," wrote Louis Pasteur, "it is always a mistake not to doubt when facts do not compel you to affirm." It is not less so in mathematics, in philosophy, in economics, in ethics, in politics. One cannot rightfully say "I am convinced that such and such a proposition is true," unless one has successfully endeavored to doubt its truth, and has, by honest consideration of all the objections that one has been able to think of, finally come to the conclusion that the proposition is indeed true.

( Mole Philosophy and Other Essays, New York : Dutton 1927. )
per THE RATIONAL AND THE SUPERRATIONAL,
The Collected Works of Cassius Jackson Keyser, Vol. II.
New York : Scripta Mathematica 1952, p. 217.

When Louis Pasteur, son of a humble tanner, was a young student in the École Normale, far from home,in the "wicked" city of Paris, he received the following letter from his father :

"Tell Chappuis"—Chappuis, a student of philosophy, and young Pasteur were chums—"Tell Chappuis that I have bottled some 1834 bought on purpose to drink the health of the École Normale during the next holidays. There is more wit in those 100 litres than in all the books on philosophy in the world, . . . Mind you tell him we shall drink the first bottle with him. Remain two good friends."

After the great man died at the age of more than three score years and ten, William Osler, Regius Professor of Medicine in the University of Oxford, wrote of him :

"He was the most perfect man who has ever entered the Kingdom of Science."

Pasteur said of his father :

"For thirty years I have been his constant care, I owe everything to him."

If, in addition to his great native gifts, Louis Pasteur had had the precious fortune to be the son of an ardent prohibitionist, or to have been educated by one, he might have been able to render as great service to humanity as William Jennings Bryan or even William H. Anderson.

( Mole Philosophy and Other Essays, New York : Dutton 1927. )
per THE RATIONAL AND THE SUPERRATIONAL,
The Collected Works of Cassius Jackson Keyser, Vol. II.
New York : Scripta Mathematica 1952, p. 219.