Once a young professor was making a sea voyage. He was a highly educated man with a long tail of letters after his name, but he had little experience of life.  

In the crew of the ship on which he was travelling was an illiterate old sailor.

Every evening the sailor would visit the cabin of the young professor to listen to him hold forth on many different subjects.He was very impressed with the learning of the young man.
One evening the sailor was about to leave the cabin after having long conversation, the professor asked,

With a long face the old sailor went away..

Next evening again as the sailor was about to leave the cabin the professor asked him, 

With longer face the sailor went away;

Next evening once again the young professor questioned the old sailor.. 

The old sailor was very unhappy.

The nextday the oldsailor came running to the cabin
and cried..

You may study all the "-ologies" of the world, but if you do not learn swimology, all your studies are useless. You may read and write books on swimming, you may debate on its subtle theoretical aspects, but how will that help you if you refuse to enter the water yourself? You must learn how to swim.