_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. Cúchulainn'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 Cúchulainn. But the best instance is found in the tale of _The Destruction of Da Derga's Hostel_, in which the _síd_-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. FOOTNOTES: [881] The religious interdictions mentioned by Cæsar (vi. 13) may be regarded as tabus, while the spoils of war placed in a consecrated place (vi. 18), and certain animals among the Britons (v. 12), were clearly under tabu. [882] Joyce, _OCR_ 332 f. [883] _Book of Rights_, ed. O'Donovan, 5. [884] _Book of Rights_, 7. [885] Ibid. 3 f. [886] _LL_ 107; O'Grady, ii. 175. [887] In Highland tales _geasa_ is translated "spells." [888] _RC_ xxii. 27 f. The story of _Da Choca's Hostel_ has for its subject the destruction of Cormac through breaking his _geasa_ (_RC_ xxi. 149 f.). CHAPTER XVIII. FESTIVALS.