De Quevedo a Lupercio Leonardo. Un testimonio singular y nuevos datos sobre la atribución de la «Carta del rey don Fernando el Católico»

In this article, a testimony of Carta del rey don Fernando el Católico is revealed. The political opuscule has been attributed to both Francisco de Quevedo and Lupercio Leonardo de Argensola. The new testimony presents interesting peculiarities, both in its structure and its contents, that allow us to advance in the analysis of the text and the modifications introduced in it; they also help to clarify certain questions about authorship. A description of the manuscript is offered, as well as a complete list of the textual variants of this testimony.