Theories are always very thin and insubstantial, experience only is tangible.
—Hosea Ballou (1771–1852) American Universalist Clergyman, Writer
In order to shake a hypothesis, it is sometimes not necessary to do anything more than push it as far as it will go.
—Denis Diderot (1713–84) French Philosopher, Critic, Writer
No theory is good unless it permits, not rest, but the greatest work. No theory is good except on condition that one use it to go on beyond.
—Andre Gide (1869–1951) French Novelist
The temptation to form premature theories upon insufficient data is the bane of our profession.
—Arthur Conan Doyle (1859–1930) Scottish Writer
The wise man regulates his conduct by the theories both of religion and science. But he regards these theories not as statements of ultimate fact but as art-forms.
—J. B. S. Haldane (1892–1964) British Biologist, Geneticist