 A problem of course is that if Cavendish is committed to the view that natural reason can form no conception of an immaterial, then she can allow that we have ideas of things that are the effect of an immaterial cause, but it is difficult to see how we could have an idea of that immaterial cause itself. So long as she “take[s] an idea to be the picture of some object” (Cavendish 1668, 74) and so long as immaterials cannot be captured in a figure or image, it would appear that she is committed to saying that we can have no ideas of immaterials at all.