English to Spanish Art/Literary Poetry & Literature expressions

"Simon was a citizen of Athens and a cobbler. When Socrates came to his workshop and began to converse, he used to make notes of all that he could remember. And this is why people apply the term "leathern" to his dialogues."

Alguien me puede explicar en qué contexto se puede utilizar o que me pase algún link a algún texto donde utilizan el término "leathern" en ese sentido?

Can anyone explain me in which context people use "leathern" in their dialogues? Maybe an example or a link to a text where it has been used?