No man is equipped for modern thinking until he has understood the anecdote of Agassiz and the fish:

A post-graduate student equipped with honours and diplomas went to Agassiz to receive the final and finishing touches. The great man offered him a small fish and told him to describe it.

Post-Graduate Student: ‘That’s only a sunfish.’

Agassiz: ‘I know that. Write a description of it.’

After a few minutes the student returned with the description of the Ichthus Heliodiplodokus, or whatever term is used to conceal the common sunfish from vulgar knowledge, family of Heliichtherinkus, etc., as found in textbooks of the subject.

Agassiz again told the student to describe the fish.

The student produced a four-page essay. Agassiz then told him to look at the fish. At the end of three weeks the fish was in an advanced state of decomposition, but the student knew something about it.

By this method modern science has arisen, not on the narrow edge of mediaeval logic suspended in a vacuum. (ABC of Reading)