Every school of thought is like a man who has talked to himself for a hundred years and is delighted with his own mind, however stupid it may be.From the Schools of Thought page of the History of Economic Thought site. I think that site is a very good starting point for serious economic study.
(J.W. Goethe, 1817, Principles of Natural Science)
update (25th December): Here is a counter balancing quote, from the HET introduction page, also from Goethe
Somebody says: "Of no school I am part,
Never to living master lost my heart,
Nor any more can I be said
To have learned anything from the dead."
That statement - subject to appeal -
Means "I'm a self-made imbecile."
(J.W. Goethe, Den Originalen, 1812)