<P> An even earlier reference can be found in "Don Quixote" by Miguel de Cervantes, from 1605 (the exception being Cervantes substituting "goats" for "sheep"): </P> <P> "Let your worship keep count of the goats the fisherman is taking across, for if one escapes the memory there will be an end of the story, and it will be impossible to tell another word of it ." </P> <P> Cervantes probably adapted the story of counting goats from a story of counting sheep in the early twelfth - century Spanish work Disciplina Clericalis . The section The King and his Story - teller (section 12) uses the idea of counting sheep humorously . Disciplina Clericalis draws mainly on literary sources from the Islamic world . Counting sheep was probably a widely recognized practice in the Islamic world before the early twelfth century . </P> <P> Serta, an American mattress manufacturer has had their own herd of "Counting Sheep" used in advertisements for the company since at least 2000 and have even sold plush toys of the sheep . </P>

Where did the expression counting sheep come from