But to descend to a humbler sphere—our own minds. We are all conscious that thoughts rush into them in a most unbidden manner, and that we pass through mental states which our analysis is unable to explain. Can any man affirm, however deep may be his philosophy, that the known laws of association of ideas are adequate to account for all the mental phenomena of which he has been conscious? Who has not had experience of severe efforts to realize something in thought, which have ended in failure, and that the right thing has suddenly come into his mind uncalled and unbidden? Not unfrequently has a sudden thought entered the mind (we know not whence it came) which has entirely changed the whole current of a previous life. Still more frequently has a happy idea occurred to us, the origin of which it is impossible to trace. Who again has not had experience of the sudden rushing of a temptation into his mind with an all but overwhelming force, even while his thoughts were occupied with subjects in no way allied to the suggestion? Many of our mental phenomena may be explained by the principle of association of ideas and other known mental powers; but who can venture to affirm that they are adequate to account for all the various states of which he has been conscious, or that some of them have not originated in suggestions from without? Scientific knowledge is certainly able to make no such affirmation. Next: there are numerous abnormal conditions to which the mind is unquestionably subject. Who will venture to affirm that he has penetrated to their depths, or ascertained the laws which regulate their action? These have a most important bearing on the present subject. They are best designated by the term phrenzy. Their aspect is very varied. They differ in many respects from mania, though they are closely allied to it. They are confined to no one race of men, but are co‐extensive with human nature. They were prevalent in the ancient world, and connected with various forms of religious belief. They display themselves with peculiar violence in the religious rites of savages. In Oriental countries at the present day, they frequently manifest themselves and assume a great variety of aspects. Examples might be easily adduced. The phrenzied fanatic often presents indications of his mind being acted on by an overwhelming external influence; and when under the influence of the rites of a degraded religion, the symptoms present no little resemblance to those which accompanied demoniacal possession.