In short, all studies have their perils, and these are among the dangers which beset the path of the inquirer into things ghostly.

He must adopt the stoical maxim: "Be sober and do not believe"-- in a hurry.
If there be truth in even one case of "telepathy," it will follow that the human soul is a thing endowed with attributes not yet recognised by science.

It cannot be denied that this is a serious consideration, and that very startling consequences might be deduced from it; such beliefs, indeed, as were generally entertained in the ages of Christian darkness which preceded the present era of enlightenment.
But our business in studies of any kind is, of course, with truth, as we are often told, not with the consequences, however ruinous to our most settled convictions, or however pernicious to society.
The very opposite objection comes from the side of religion.

These things we learn, are spiritual mysteries into which men must not inquire.

This is only a relic of the ancient opinion that he was an impious character who first launched a boat, God having made man a terrestrial animal.