"The Proof Of The Pudding Is In The Eating"
Context: Still arguing about enchantments, Sancho Panza assures his master that the Princess Micomicona was really a damsel named Dorothea, and that the giant and his blood were wineskins in the store room. In trying to convince Don Quixote, he uses the common Spanish proverb: "It will be seen in the frying of the eggs," because the condition of eggs is not apparent until they are broken into the pan for frying. Motteux, in his 1701 translation, uses a corresponding English proverb. As he phrased Sancho's speech:
. . . Gadzookers sir, are not the skins all hacked and slashed within there at your bed's-head, and the wine all in a puddle in your chamber? But you'll guess at the meat presently, by the sauce; the proof of the pudding is in the eating, master. . . .