Note (return) — Chapter XVII

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.