of the tribe and the making of rain or sunshine, and the processes of growth depend.  They must therefore be careful of their actions, and hence they are hedged about with tabus which, however unmeaning, have a direct connection with their powers.  Out of such conceptions the Irish kingly geasa arose.  Their observance made the earth fruitful, produced abundance and prosperity, and kept both the king and his land from misfortune.  In later times these were supposed to be dependent on the “goodness” or the reverse of the king, but this was a departure from the older idea, which is clearly stated in the Book of Rights.[884] The kings were divinities on whom depended fruitfulness and plenty, and who must therefore submit to obey their geasa.  Some of their prerogatives seem also to be connected with this state of things.  Thus they might eat of certain foods or go to certain places on particular days.[885] In primitive societies kings and priests often prohibit ordinary mortals from eating things which they desire for themselves by making them tabu, and in other cases the fruits of the earth can only be eaten after king or priest has partaken of them ceremonially.  This may have been the case in Ireland.  The privilege relating to places may have meant that these were sacred and only to be entered by the king at certain times and in his sacred capacity.

As a reflection from this state of things, the heroes of the sagas, Cuchulainn and Fionn, had numerous geasa applicable to themselves, some of them religious, some magical, others based on primitive ideas of honour, others perhaps the invention of the narrators.[886]

Geasa, whether in the sense of tabus or of obligations, could be imposed by any one, and must be obeyed, for disobedience produced disastrous effects.  Probably the obligation was framed as an incantation or spell, and the power of the spell being fully believed in, obedience would follow as a matter of course.[887] Examples of such geasa are numerous in Irish literature.  Cuchulainn’s father-in-law put geasa on him that he should know no rest until he found out the cause of the exile of the sons of Doel.  And Grainne put geasa on Diarmaid that he should elope with her, and this he did, though the act was repugnant to him.

Among savages the punishment which is supposed to follow tabu-breaking is often produced through auto-suggestion when a tabu has been unconsciously infringed and this has afterwards been discovered.  Fear produces the result which is feared.  The result is believed, however, to be the working of divine vengeance.  In the case of Irish geasa, destruction and death usually followed their infringement, as in the case of Diarmaid and Cuchulainn.  But the best instance is found in the tale of The Destruction of Da Derga’s Hostel, in which the sid-folk avenge themselves for Eochaid’s action by causing the destruction of his descendant Conaire, who is forced to break his geasa.  These are first minutely detailed; then it is shown how, almost in spite of himself, Conaire was led on to break them, and how, in the sequel, his tragic death occurred.[888] Viewed in this light as the working of divine vengeance to a remote descendant of the offender by forcing him to break his tabus, the story is one of the most terrible in the whole range of Irish literature.