soul of pitcher is incorrectly written and should be written as 'soul pitcher' being its meaning:
Expression of the old Spanish saying who is so innocent, naive and candid that it is object of ridicule and jokes because it has so hollow head and so little understanding that only say nonsense; So says the clergyman Don Quixote in chapter XXVI of part: "... and to you, soul of pitcher, who you has embedded in the brain that you are Knight, vencéis Giants and prendéis miscreants? Walk congratulations... "