Here the reflection in the mirror or water is held to be the person himself, because savages do not understand the nature of the reflected image.

It is the person himself, but has no corporeal substance; therefore the reflection must be his ghost or spirit.

But if the spirit appears once it is an omen that it will appear again; and in order that it may do so the man will have to die so that the spirit may be set free from the body in order to appear.

The special reason for not looking into a mirror at night would thus be because the night is the usual time for the appearance of spirits.

The fable of Narcissus, who fell in love with his own image reflected in the water and was drowned, probably arose from the superstition against seeing one's image reflected in water.