Book of the Greatness of the Sword) is a 16th-century Spanish treatise on fencing written by Don Luis Pacheco de Narváez, who is considered one of the founding fathers of Spanish fencing (destreza) and the disciple of Jerónimo Sánchez de Carranza.

The treatise consists of five chapters and starts with the title page which states: "Book of the Greatness of the Sword, in which many secrets which the Commander Jerónimo de Carranza composed, are declared.

Dedicated to Don Philip III King of Spain, and of the greater part of the world, our lord."

Luis Pacheco de Narváez persuasively discusses the skill in general, as well as the reason and evidence that destreza is considered a true science.

Indeed, the treatise is written in sophisticated language with examples from geometry, mathematics, logic, Aristotelian works, Pythagorus, as well as an explanation of human temperament types and their classification.