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
Cuchulainn not to eat dog's flesh, and of Conaire never to chase
birds--also point to totemism.

In some cases _geasa_ were based on ideas of right and wrong, honour or
dishonour, or were intended to cause avoidance of unlucky days. Others
are unintelligible to us. The largest number of _geasa_ concerned kings
and chiefs, and are described, along with their corresponding
privileges, in the _Book of Rights_. Some of the _geasa_ of the king of
Connaught were not to go to an assembly of women at Leaghair, not to sit
in autumn on the sepulchral mound of the wife of Maine, not to go in a
grey-speckled garment on a grey-speckled horse to the heath of Cruachan,
and the like.[883] The meaning of these is obscure, but other examples
are more obvious and show that all alike corresponded to the tabus
applying to kings in primitive societies, who are often magicians,
priests, or even divine representatives. On them the welfare 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,