makes its nom. plur. _gruda_ for O. Ir.
_grad_.[11]

[11] The infinitive _bith_ for O. Ir. _buith_ (91), the dative _cinn_
for O. Ir. _ciunn_ (98, 135), the nom. pl. _sligthi_ for O. Ir. _sligid_
(which I have restored in Sec. 49), the confusion between _do_ and _di_
(e.g. 83), and other details are probably due to the Middle-and
Modern-Irish transcribers.

On linguistic grounds, then, I should say that our collection was made
some time during the second half of the ninth century. That it cannot be
dated earlier is also apparent from another consideration. Professor
Zimmer has taught us to search in every ancient Irish text for
indications of its having been composed either before or after the
Viking period. I find no words from the Norse language in the Triads,
or, if there are any, they have escaped me; but there are two distinct
references to the Viking age. In Sec. 232, a Viking in his hauberk (_Gall
ina luirig_) is mentioned as one of three that are hardest to talk to;
and, in Sec. 44, Bangor in Co. Down is called unlucky or unfortunate, no
doubt, as the gloss says, because of the repeated plunderings and
destruction of its monastery by the Norse during the early part of the
ninth century (A.D. 823, 824).

In endeavouring to trace the origin of the Triad as a form of literary
composition among the Irish, one must remember that it is but one of
several similar enumerative sayings common in Irish literature. Thus the
collection here printed contains three duads (124. 133. 134), seven
tetrads (223. 230. 234. 244. 248. 251. 252), and one heptad (235). A
whole Irish law-book is composed in the form of heptads;[12] while
triads, tetrads, &c., occur in every part of the Laws.[13] Such
schematic arrangements were of course a great aid to memory.

[12] See _Ancient Laws of Ireland_, vol, v., pp. 118-373.

[13] Thus in the first volume of the Laws we find duads on p. 228, 15;
294, 27; triads on p. 50, 9. 27; 230, 4; 264, 20; 288, 28; tetrads 40,
21; 54, 7; 64, 1; 240, 24; 256, 4, &c.; 272, 25; 274, 3, &c.; pentads
30, 21; 50, 32; 90, 29; 102, 6; hexads 68, 11; 248, 7: a heptad 134, 9;
an ennead 16, 20.

If the Triad stood alone, the idea that it owes its origin to the effect
of the doctrine of the Trinity upon the Celtic imagination might
reasonably be entertained. The fact that this doctrine has led to many
peculiar phenomena in Irish folklore, literature, and art has frequently
been pointed out. Nor would I deny th