A manufacturer learns details personally and makes nearly daily mistakes; these errors are helps in the form of experience if heeded. Barnum’s anecdote of a Yankee tin-peddler cheated on merchandise quality who resolved never to be cheated the same way again exemplifies purchased experience. Barnum praises Cuvier for knowing natural history so thoroughly that from a single bone he could deduce the animal’s complete form. When students tried deceiving him with a costumed person in a cow skin, Cuvier immediately recognized the deception through analyzing anatomical properties.