Ragione di adoprar sicuramente l'Arme, si da offesa come da difesa

The Ragione di adoprar sicuramente l'Arme, si da offesa come da difesa was a famous treatise on fencing published by Giacomo di Grassi in 1570. The text was later translated into English and published again in 1594, as Di Grassi, His True Arte of Defence. The translation of Di Grassi was one of the three premiere fencing texts known from Elizabethan England.

The main teachings of the book were that weapons of the same length are used similarly, the thrust is preferred to all other attacks, as well as specifics on how to thrust and handle specific weapons.