[860] Justin, xxiv, 4; Cicero, _de Div._ i. 15. 26. (Cf. the two magic crows which announced the coming of Cúchulainn to the other world (D'Arbois, v. 203); Irish _Nennius_, 145; O'Curry, _MC_ ii. 224; cf. for a Welsh instance, Skene, i. 433.) [861] Joyce, _SH_ i. 229; O'Curry, _MC_ ii. 224, _MS Mat._ 284. [862] _IT_ i. 129; Livy, v. 34; Loth, _RC_ xvi. 314. The Irish for consulting a lot is _crann-chur_, "the act of casting wood." [863] Cæsar, vi. 14. [864] O'Curry, _MC_ ii. 46, 224; Stokes, _Three Irish Homilies_, 103. [865] Cormac, 94. Fionn's divination by chewing his thumb is called _Imbas Forosnai_ (_RC_ xxv. 347). [866] _Antient Laws of Ireland_, i. 45. [867] Hyde, _Lit. Hist. of Ireland_, 241. [868] Justin, xliii. 5. [869] O'Grady, ii. 362; Giraldus, _Descr. Camb._ i. 11. [870] Pennant, _Tour in Scotland_, i. 311; Martin, 111. [871] Richardson, _Folly of Pilgrimages_, 70. [872] Tertullian, _de Anima_, 57; _Coll. de Reb. Hib._ iii. 334. [873] Campbell, _Superstitions_, 263; Curtin, _Tales_, 84. [874] Lucan, ed. Usener, 33. [875] See examples in O'Curry, _MS Mat._ 383 f. [876] Miss Hull, 19, 20, 23. [877] _LU_ 55. [878] _RC_ xii. 98, xxi. 156, xxii. 61. [879] _RC_ xv. 432; _Annals of the Four Masters_, A.M. 2530; Campbell, _WHT_ iv. 298. [880] See "Adamnan's Second Vision." _RC_ xii. 441. CHAPTER XVII. TABU. The Irish _geis_, pl. _geasa_, which may be rendered by Tabu, had two senses. It meant something which must not be done for fear of disastrous consequences, and also an obligation to do something commanded by another. As a tabu the _geis_ had a large place in Irish life, and was probably known to other branches of the Celts.[881] It followed the general course of tabu wherever found. Sometimes it was imposed before birth, or it was hereditary, or connected with totemism. Legends, however, often arose giving a different explanation to _geasa_, long after the customs in which they originated had been forgotten. It was one of Diarmaid's _geasa_ not to hunt the boar of Ben Gulban, and this was probably totemic in origin. But legend told how his father killed a child, the corpse being changed into a boar by the child's father, who said its span of life would be the same as Diarmaid's, and that he would be slain by it. Oengus put _geasa_ on Diarmaid not to hunt it, but at Fionn's desire he broke these, and was killed.[882] Other _geasa_--those of Cúchulainn not to eat dog's flesh, and of Conaire never to chase birds--also point to totemism.