At the beginning of this century, Wigner put forward the theory of continental drift, which met with strong opposition because his theory was based on the assumption of unidentified forces sufficient to cause continental drift. We can now accept Wigner's theory. This is not because we have identified the power to cause the continent to drift, but because the new instruments eventually enable us to confirm the movement of the continent through observation.
 With the help of probability theory and mathematical statistics, science has shifted from the description of a single phenomenon to the study of things as a whole is best illustrated by the above examples.