  But what on Desgabets’s account is the difference between a simple conception and a precipitous judgement? What is the criterion for distinguishing one from the other? In his Supplément, he offers the example of imaginary space. When we speak of imaginary space, many are persuaded that it does not include any judgement on their part, but if one looks closely, one sees that the simple object of conception here is space and extension with its perceived dimensions from which we form a judgement concerning its imaginary nature. Similarly, when someone approaches fire and has the sensation of heat, pain or pleasure, he may be persuaded that the heat he feels is in the fire just as he perceives it, since this sensation is known to him clearly. But, he has erred because of a tacit judgement. His conception of the fire and of the heat, as well as of his intervening judgement are all the immediate and true objects of his thought. These all qualify as simple conceptions in so far as they relate to their true object. But, that the heat is in the fire by which it is claimed that the heat in us resembles that of the fire, is a tacit judgement which is false. In this sense, the illusions that are attributed to the senses always involve false judgement. It is a genuine question to ask about a baton partially submerged in water whether it is straight or curved, but whether the baton, straightness, curvature etc., are real things, is not. Simple conceptions are the mind’s grasp of things as they are in themselves, which is to say, in relation to their essence as extended substances, or as thinking minds. Space, as an attribute of matter, is extended in three dimensions, and sensations, as attributes of the mind, are perceptions not qualities of material objects.