Every person who has studied, even in the most cursory manner, the checkered page of human life, must have observed that there are in continual operation through mankind some great secret moral agents, the powers of which are exerted within the heart, and beyond the reach of the consciousness or observation of the individual himself who is subject to their influence. There is a steadfastness of virtue in some high-minded men, which enables them to resist the insidious temptations of the bad demon; there is also a stern stability of vice often found in the unfortunate outlaw, which disregards, for a time, the voice of conscience, and spurns the whispered wooing of the good principle, "charm it never so wisely;" yet the real confessions of the hearts of those individuals would show traces enough of the agency of the unseen power to prove their want of title to an exception from the general rule which includes all the sons of Adam. We find, also, that extraordinary moral effects are often produced, in a dark and mysterious manner, from physical causes: every medical man has the power of recording, if he has had the faculty of observing, changes in the minds, principles, and feelings of patients who have come through the fiery ordeal of a terrible disease, altogether unaccountable on any rules of philosophy yet discovered. Not many years ago, a well-dressed young woman called one evening upon me, and stated that her lady, whose name, she said, would be communicated by herself, had been ill for some days, and wished me to visit her privately. I asked her when she required my attendance; and got for answer, that she, the messenger, would conduct me to the residence of the patient, if it was convenient for me to go at that time. I was disengaged, and agreed to accompany the young woman as soon as I had given directions to my assistant regarding the preparation of some medicines which required the application of chemical rules. To be ingenuous, I was a little curious to know the secret of this private call; for that there was a secret about it was plain, from the words, and especially the manner, of the young woman, who spoke mysteriously, and did not seem to wish any questions put to her on the subject of her mission. The night was dark, but the considerate messenger had provided a lantern; and, to anticipate my scruples, she said that the distance we had to go would not render it necessary for me to take my carriage--a five-minutes' walk being sufficient to take us to our destination.