In the preceding chapter we have given a very brief epitome of the various beliefs regarding immortality and the invisible world held by the civilised nations of the earth, from the earliest dawn of history to the present day. It is now time to say something about the object of this book, as well as to define the position from which we mean to start in pursuance of this object. We shall therefore commence by dividing those who concern themselves about our theme into three great classes.

In the first place, we have those who are so absolutely certain of the truth of their religion, and of the immortality which it teaches, that they are not qualified to entertain or even to perceive any scientific objection. They acknowledge that certain deductions made by men of science appear to contradict the truth of their religion. But these they regard as premature conclusions, averring that when the laws of nature have been more deeply investigated, there will be found a perfect concord between science and revelation. Certain scientific truths they readily assent to, and it is only the altogether human superstructure of speculation built upon these that they profess to question.