All the world over and at all times there have been practical men, absorbed in irreducible and stubborn facts; and at all times there have been men of philosophical temperament, who have been absorbed in the weaving of general principles.
I am suggesting that a good many of the people, including prominent ones, who are now regarded as scientists are really little more than technicians. Only once in a while do we get a really swagger scientist.
In formal logic, a contradiction is a signal of a defeat; but in the evolution of real knowledge it marks the first step in progress towards a victory. This is one great reason for the utmost toleration of variety of opinion.