 Fourth, sections 12–14 declare it is “manifestly by impulse” that ideas are caused in minds (E 2.8.11). A little reflection is taken to show that when we perceive a body, motions of insensible particles convey motions to parts of our bodies that ultimately result in sensory ideas. If it is true that bodies acton our sense only by impulse, this is a reason to accept the characterization of SQs in Essay 2.8.10.