  If the most important distinction of the Specimen Dynamicum  with respect to physics is between active and passive forces, its  most important distinction with respect to metaphysics is between  what Leibniz calls “primitive” and  “derivative” forces. He holds that while derivative  forces are of primary interest to the working physicist, they are  metaphysically secondary to primitive forces, and he speaks of the  former as being “modifications” or  “limitations” of the latter (GM VI.236/AG 119). Although  the topic of the relationship between derivative and primitive forces quickly takes us away from Leibniz’s treatment of physics and into  the heart of his metaphysics, it should be worthwhile to at least  call attention to this interface where what we are inclined to think  of as Leibniz’s physics so clearly bumps up against – indeed  overlaps with – what we are inclined to think of as his  metaphysics. 