In Norway and Iceland certain men were said to be _eigi einhamir_, not
of one skin, an idea which had its roots in paganism. The full form of
this strange superstition was, that men could take upon them other
bodies, and the natures of those beings whose bodies they assumed. The
second adopted shape was called by the same name as the original
shape, _hamr_, and the expression made use of to designate the
transition from one body to another, was at _skipta hömum_, or _at
hamaz_; whilst the expedition made in the second form, was the hamför.
By this transfiguration extraordinary powers were acquired; the
natural strength of the individual was doubled, or quadrupled; he
acquired the strength of the beast in whose body he travelled, in
addition to his own, and a man thus invigorated was called _hamrammr_.

The manner in which the change was effected, varied. At times, a dress
of skin was cast over the body, and at once the transformation was
complete; at others, the human body was deserted, and the soul entered
the second form, leaving the first body in a cataleptic state, to all
appearance dead. The second hamr was either borrowed or created for
the purpose. There was yet a third manner of producing this effect-it
was by incantation; but then the form of the individual remained
unaltered, though the eyes of all beholders were charmed so that they
could only perceive him under the selected form.

Having assumed some bestial shape, the man who is _eigi einhammr_ is
only to be recognized by his eyes, which by no power can be changed.
He then pursues his course, follows the instincts of the beast whose
body he has taken, yet without quenching his own intelligence. He is
able to do what the body of the animal can do, and do what he, as man,
can do as well. He may fly or swim, if be is in the shape of bird or
fish; if he has taken the form of a wolf, or if he goes on a