We shall more readily understand the nature and genesis of all these hallucinations, and of normal and abnormal illusions, if we study another phenomenon of frequent occurrence which I myself have often had occasion to observe.  I mean the illusion or hallucination which does not consist in the absolute projection of an internal image with an external semblance of reality, but which presents it in the twilight as an object of uncertain form, either in a room or out of doors.  It often happens, as I and others have experienced from childhood, that a dress or other object lying by chance on a chair, or on the ground, or hanging on a piece of furniture or a peg, seen in connection with the other things near it, is transformed into a person or animal, in a sitting or standing posture or lying at full length, as if it had been a spectre or phantasm; somewhat like the figures which we all take pleasure in tracing in the strange and mobile forms of clouds.  The fantastic figure sometimes appears instantaneously and at the first glance, sometimes it is only gradually made out; but in both cases, as we shall see, its genesis is the same.  Although in the former case that which in the latter is gradually developed appears to be developed all at once, yet in reality it passes through the same stages.

Let us now consider the second mode; and in order to be perfectly accurate, I will describe one out of many apparitions which I saw so recently that its gradual formation is retained distinctly in my memory.  On a small three-legged table beside my bed there was a little oval mirror, on which hung a woman’s cap, which fell partly over the glass:  there was also an easy chair, on which I had thrown my shirt before going to bed, while my shoes were as usual on the floor.  I awoke towards morning, and as I chanced to look round the large room, in the uncertain light of a night-light which was almost burnt out, my eyes fell upon the easy chair.  Immediately I seemed to see a head above it, corresponding to the mirror, and a vague and confused image of a person seated there.  As I am accustomed to do in similar cases, I closed my eyes for a little, and on reopening them I looked at the appearance with attention and interest; this time the person or phantasm had a less confused outline, although I did not see the form distinctly, nor the features, nor its precise position.  Yet in this second observation, I obtained an idea of it as a whole, and in details.

On further examination the face and person stood out more clearly, and the features became more distinct, the longer I looked.  Each accidental fold or shadow on the cap was transformed into bright eyes, strongly marked eyebrows, into the nose, mouth, hair, beard, and neck; so that as I went on I had before me a perfectly chiselled face corresponding to the type which had first flashed across my mind as the confused impression of a face conveyed by the cap and mirror.  The same process of evolution was