  As part of the recent “upsurge” in Marchia studies, his theory of virtus derelicta has also been reconsidered (Zanin 2006b; Marchia 2006b, 2006c). It is clear that the basic idea of a force left behind had been circulating for several decades, so Marchia did not develop the theory ex nihilo. Nevertheless, Marchia appears to have spent much more time and energy on projectile motion than his predecessors. Aristotle himself did not go on at great length and in much detail, which probably explains why his theory was so flawed. It seems, then, that the scientific problem only became a significant issue among natural philosophers with Francis of Marchia. Despite its obvious improvement on Aristotle, before the 1330s Marchia’s theory was opposed by his Franciscan successor at Paris Francis of Meyronnes and by Meyronnes’ follower Himbert of Garda, another Franciscan, although it was treated more favorably by Francis Marbres (a.k.a. John the Canon) and the Franciscan Nicholas of Bonet. But none of them analyzed it extensively. Already in the mid-1320s, however, Gerard Odonis embraced it wholeheartedly and in detail. Therefore, although the famous theories put forth by John Buridan and Nicole Oresme in the following decades in lengthy discussions differ in some ways from Marchia’s, the similarities between the theories and the mere fact that Buridan and Oresme took the issue of projectile motion so seriously surely point to Marchia’s impact. In this way, Marchia most probably had an impact on the development of the theory of inertia.