many forms.  The priestesses of Sena could assume the form of animals, and an Irish Circe in the Rennes Dindsenchas called Dalb the Rough changed three men and their wives into swine by her spells.[1112] This power of transforming others is often described in the sagas.  The children of Lir were changed to swans by their cruel stepmother; Saar, the mother of Oisin, became a fawn through the power of the Druid Fear Doirche when she rejected his love; and similarly Tuirrenn, mother of Oisin’s hounds, was transformed into a stag-hound by the fairy mistress of her husband Iollann.[1113] In other instances in the sagas, women appear as birds.[1114] These transformation tales may be connected with totemism, for when this institution is decaying the current belief in shape-shifting is often made use of to explain descent from animals or the tabu against eating certain animals.  In some of these Irish shape-shifting tales we find this tabu referred to.  Thus, when the children of Lir were turned into swans, it was proclaimed that no one should kill a swan.  The reason of an existing tabu seemed to be sufficiently explained when it was told that certain human beings had become swans.  It is not impossible that the Druids made use of hypnotic suggestion to persuade others that they had assumed another form, as Red Indian shamans have been known to do, or even hallucinated others into the belief that their own form had been changed.

By a “drink of oblivion” Druids and other persons could make one forget even the most dearly beloved.  Thus Cuchulainn was made to forget Fand, and his wife Emer to forget her jealousy.[1115] This is a reminiscence of potent drinks brewed from herbs which caused hallucinations, e.g. that of the change of shape.  In other cases they were of a narcotic nature and caused a deep sleep, an instance being the draught given by Grainne to Fionn and his men.[1116] Again, the “Druidic sleep” is suggestive of hypnotism, practised in distant ages and also by present-day savages.  When Bodb suspected his daughter of lying he cast her into a “Druidic sleep,” in which she revealed her wickedness.[1117] In other cases spells are cast upon persons so that they are hallucinated, or are rendered motionless, or, “by the sleight of hand of soothsayers,” maidens lose their chastity without knowing it.[1118] These point to knowledge of hypnotic methods of suggestion.  Or, again, a spectral army is opposed to an enemy’s force to whom it is an hallucinatory appearance—­perhaps an exaggeration of natural hypnotic powers.[1119]

Druids also made a “hedge,” the airbe druad, round an army, perhaps circumambulating it and saying spells so that the attacking force might not break through.  If any one could leap this “hedge,” the spell was broken, but he lost his life.  This was done at the battle of Cul Dremne, at which S. Columba was present and aided the heroic leaper with his prayers.[1120]