70. Intuition belongs only to perceptive powers, to those by which the subject affected distinguishes between its affection and the object causing it. We do not pretend to say that this must be a reflex distinction, but simply that the internal act must refer to an object. If we suppose a being to experience various affections, but to neither refer them to any object, nor reflect upon them itself; this being can never with propriety be said to have true intuition, for intuition seems to involve the exercise of an activity occupied with a present object. The object of intuition need not always be an external being; it may be an affection or action of the soul made objective by a reflex act. 71. The sensations which are with the greatest propriety called intuitive, are those of sight and touch; for, since it is impossible for us, when we perceive extension, to regard it as a purely subjective fact, the acts of seeing and feeling necessarily involve relation to an object. The other senses, although they may have a certain relation to extension, do not perceive it directly, so that were they to stand alone, they would partake more of the affective than of the intuitive; that is, the soul would be affected by the sensations, but would be under no necessity of referring them to external objects. If reflection made upon these sensations come to teach, as in effect it would teach that their cause is a being distinct from those that experience them, there would be no true intuition; not for the senses, because they would remain foreign to complex combinations; nor for the understanding, because it would then know the cause of the sensations, not by intuition, but by discursion. 72. We infer from this, that not every sensation is an intuition; and that the imaginary reproductions of past sensations, or the imaginary production of possible sensations, although repeatedly styled intuitions, are, since they do not refer to an object, unworthy of the name. We ought, nevertheless, to observe that the phenomena of purely internal sensibility do, perhaps, owe to the habit of reflection their non-reference to objects. Reflection perceives the difference of time, the more or less vividness of sensations, their greater or less constant connection, and also other circumstances; and it is enabled by these to distinguish between representations which do really refer to an object, such as external sensations, and those that have only a past or possible object, such as purely internal representations. Thus experience teaches us that the purely internal sensibility, wholly abandoned to itself, transfers whatever is presented to it to the external world, without the aid of reflection, and converts imaginary appearances into realities. This is verified in sleep, or even in our waking hours, when by some cerebral inversion the sensibility works by itself alone, and entirely free of reflection.