Fish can't climb trees

This quotation alludes to a long-standing allegorical framework. It is inappropriate to judge an animal by focusing on a skill which the creature does not possess. A fish is specialized to swim superbly, and its ability to climb a tree is non-existent or rudimentary. In the domain of education this allegory has been employed repeatedly for more than one hundred years. Hence, this quotation is built on ideas that have been in circulation among educators for many decades.