urrence.

It would seem, that when the blood is heated or the nervous system
over-strained, we are liable to attach reality to the mere productions
of the imagination. There must be few who have not had personal
experience of this affection. In the first night of a febrile attack,
and often in the progress of fever, the bed-hangings appear to the
patient swarming with human faces, generally of a disagreeable and
menacing expression. With some, opium will produce a host of similar
visitants. In much illness, I have often myself taken this drug, and
always hoped it would provide me a crop of apparitions that I might
analyse. But I was disappointed; opium I found to give me only a great
tranquillity and clearness of thought. Once or twice only have I had a
vision, and that but a transitory landscape. I used in vain to look upon
that _black mixture_ which lies before one in the dark, and try to make
its fragmentary lights arrange themselves into definite shapes. And I
have imaged to my mind familiar scenes or faces, (as in the daytime a
strong conception will half realise such,) but they were not more
distinct then than formerly,--ideas only and perfectly transient. But,
as I have said, once or twice I have had the satisfaction of seeing a
bright and coloured landscape spread before my view; yet unlike reality,
and more resembling a diorama, occupying a rectangle on the black
mixture before my eyes. It was not a known and familiar scene, but a
brilliant sketch, made out of materials I remembered, but could not by a
deliberate effort _have combined_ so effectively. It was a spontaneous
throe of the imagination, which had force to overpersuade the organs of
perception.

How well did Shakspeare understand this creative power of the
fancy!--the air-drawn dagger of Macbeth, and his test--"come, let me
clutch thee!" are physiologically perfect. Nor less perfect or true to
nature, is the conception of the ghost of Banquo haunting the kingly
murderer. The ghost, it is obvious, however, should not in the play
appear bodily. The audience are in the position of the guests at the
royal supper-table, who saw it not. I wonder how in Shakspeare's time
the stage-directions ran upon this point. Probably as now. Though
Shakspeare wrote for all times, he was probably wise enough to act for
the present. Or perhaps, with no disrespect to his unequalled genius, he
understood not the principles of which he exactly portrayed the
workings, and wa