General Science. 
sn 
sions, may be traced to such fantastical objects of prior belief as 
are incorporated in the various systems of superstition, which 
for ages have possessed the minds of* the vulgar.” In the suc- 
ceeding and by far the most considerable part of this treatise, the 
research is of a novel kind. Since apparitions are ideas equalling 
or exceeding in vividness actual impressions, there ought to be 
some important and definite laws of the mind which have given 
rise to this undue degree of vividness. It is therefore chiefly 
for the purpose of explaining such laws that the present disserta^ 
tion is written. But I here enter into a perfectly new field of 
research, where far greater difficulties are to be encountered than , 
I anticipated. The extent of them can indeed be only estimat- 
ed by the metaphysician.” The laws which govern the vivid- 
ness of our feelings. Dr Hibbert explains in the various tran- 
sitions which the mind undergoes, 1st, From perfect sleep to 
the common state of watchfulness ; 2dly, From the ordinary tran- 
quil state of watchfulness to that extreme condition of mental 
excitement which is conceived to be necessary for the production 
of spectral illusions; 3dly, From perfect and imperfect sleep 
to dreams and somnambulism. These laws meet with very 
striking illustrations ; which, the author adds, are not more 
numerous than the treatise requires, as my object is not only to 
render the principles which I have inculcated as intelligible as 
possible, but to direct the attention of the reader, less to the 
vulgar absurdities which are blended with ghost-stories, than to 
the important philosophical inferences which are frequently to 
be deduced from them. The subject of apparitions has, indeed,, 
for centuries, occupied the attention of the learned ; but seldom 
without reference to superstitious speculations. It is time, how- 
ever, that these illusions should be viewed in a perfectly diffe- 
rent light ; for, if the conclusions to which I have arrived be' 
correct, they are calculated, more than almost every other clas& 
of mental phenomena, to throw considerable light upon certain 
important laws connected with the physiology of the human 
mind.” . 
32. Ancient Inscriptions on Sheets of Lead.^Vvior to the* 
invasion of Spain by the French armies, sheets of lead, in- 
scribed with characters approaching the Arabic, were found 
rolled up, and concealed in fissures of rocks near the (|ty of 
