Business, books, conversation; for all of these, a fool is totally incapacitated, and except condemned by his station to the coarsest drudgery, remains a useless burthen upon the earth.
 David Hume, An Enquiry Concerning the Principles of Morals (1751). copy citation

Context

“Self-satisfaction, at least in some degree, is an advantage, which equally attends the fool and the wise man: But it is the only one; nor is there any other circumstance in the conduct of life, where they are upon an equal footing. Business, books, conversation; for all of these, a fool is totally incapacitated, and except condemned by his station to the coarsest drudgery, remains a useless burthen upon the earth. Accordingly, it is found, that men are extremely jealous of their character in this particular; and many instances are seen of profligacy and treachery, the most avowed and unreserved; none of bearing patiently the imputation of ignorance and stupidity.” source