  Another important consequence of the true nature of sensible qualities is that the senses are not the source of error. This is a theme found in Descartes that depends on an important distinction between the scope of the two basic operations of the mind—that of the intellect and that of the will. The functions of assenting and dissenting are performed only by the will, while those of perception and conception are performed by the senses and intellect. For Desgabets, as for Descartes, simple conception is always true and conforms to its object, while error is a product of precipitous judgement. But unlike Descartes, Desgabets concluded that everything that is conceived of is a simple conception, not just God, soul and body. For Desgabets, a thing truly conceived, actually exists. Errors and so-called beings of reason which are said not to exist outside our conceptions, are not really conceptions, and are “… nothing but a false judgement which extends itself beyond perception. Likewise the failure that is often attributed to the senses is equally nothing but a precipitous judgement by which one says that the senses do not know” (OPD 6: 227). According to Desgabets, after having distinguished simple ideas from judgement in the Third Meditation, Descartes erred gravely in placing chimeras and other such beings of reason among the number of objects of simple conception. It was this that led to Descartes’s fundamental error—the reversal of the basic truth that the first operation of the mind has only real things for its object. By including chimerical beings among the objects of conception Descartes opened the door to the possibility of thoughts without true objects. But, judgement or the extension of the will beyond the domain of what is conceived is the true source of chimeras and error (OPD 4: 103).