P16: From the mere fact that we imagine a thing to have some likeness to an object that usually affects the Mind with Joy or Sadness, we love it or hate it, even though that in which the thing is like the object is not the efficient cause of these affects.

Dem.: What is like the object, we have (by hypothesis) regarded in the object itself with an affect of Joy or Sadness. And so (by P14), when the Mind is affected by its image, it will immediately be affected also with this or that affect. Consequently the thing we perceive to have this same {quality} will (by P15) be the accidental cause of Joy or Sadness; and so (by P15 C) although that in which it is like the object is not the efficient cause of these affects, we shall still love it or hate it, q.e.d.