Apprehension is an operation of the mind which makes it perceive a thing; it is the same thing as perception. The soul, according to Father Malebranche, can perceive things in three ways; by pure understanding, by imagination, and by the senses. Through pure understanding it perceives incorporeal things, universal truths, common notions, the idea of perfection, and in general all its thoughts, when it knows them by means of a self reflection. It even perceives material things, dimensions with their properties, through pure understanding, for only understanding could perceive a perfect circle and square, a figure with calculated sides, and the like; these kinds of perceptions are called pure concepts or pure intellections , because it is in no way necessary for the mind to form corporal images in the brain to present all these things to itself. Through imagination the soul perceives only material beings, while they are absent it makes them present by forming, so to speak, images in the brain; it is in this way we imagine all kinds of figures. These kinds of perceptions can be called imaginations , because the soul presents these objects to itself by forming its own images in the brain; and because one cannot form images of incorporeal things, it follows that the soul cannot imagine them. Finally the soul perceives only tangible and gross objects by the senses: while they are present they make impressions on the exterior organs of the body, and that impression is communicated to the brain; these kinds of perceptions are called feelings or sensations .

When Father Malebranche declares that corporal things are represented to us by our imagination and concepts by our pure intelligence, does he himself really understand? In both cases is it not equally a thought of the mind, and is it less so when thinking about a mountain, which is corporal, than thinking about an intelligence which is incorporeal? Will anyone say that the operation of the mind, which acts by virtue of traces of our brain by means of corporal objects, is the imagination; and the operation of the mind independent of these traces is pure intelligence? When the Cartesians talk to us of these traces of the brain, are they saying anything serious? With what type of microscope have they perceived the traces that form the imagination? And were they to perceive them, could they ever know that the mind has no need for it for all its operations, even the most incorporeal?

To speak more to the point, let us say that the faculty of thinking is always the same, always equally incorporeal, no matter what object it focuses on. One can by no means prove its incorporeal nature, by one object more than another; neither more by what is called intellection, nor by what is called imagination . Do not angels think about corporal and incorporeal objects? Because of that do we take it into our heads to distinguish in them the imagination from pure intelligence? Do they need traces of the brain on one hand more than the other? It is thus with ourselves: as soon as our mind thinks, it thinks absolutely by means of a incorporeal quality as true as pure spirits; whether it be called imagination or pure intelligence.

But when a body appears to the mind, does one not say that it forms a phantom in it? The word phantom , accepted by the ancient Philosophers, means nothing regarding the subject at hand, or means only the object interior to our mind, insofar as it is thinking about a body. Now that interior object is equally incorporeal, whether thinking about bodies, or thinking about minds, even though in either case it might need the help of the senses. I conclude that the essential difference between the imagination and pure intelligence that some have wished to establish is but pure imagination.