"[O]ne of the most interesting aspects in Fabri's physics is the wholehearted adoption of the important principle of conservation of rectilinear motion (...CRM) - a direct result of an impetus which... tends to conserve itself in the absence of obstacles or hindrences, and the possibility of motion in a vacuum... CRM is often referred to as "inertia", but this problematic term is both anachronistic and misleading. The word... (...meaning "laziness") was first utilized in a physical sense by Johannes Kepler, to mean a tendency of bodies to come to rest once they are set in motion... It was subsequently used, in a different sense - meaning the reluctance of bodies in rest to be set in motion - by Descartes... and even by Fabri himself. This notion, as... expressed in Newton's first law... could be regarded merely as a "less important aspect of inertia" than in his second law... it is also clear that the classical (or Newtonian) concept cannot be fully expressed and understood without Newton's third law and his concept of force..."