From the Italians we pass on to their close kinsmen the Kelts. We are told by Polybius[49] that when the Gauls entered Italy, their wealth consisted of their cattle and gold ornaments, but although an argument will be offered below to show that the cow was the monetary unit of both Gauls and Germans, we have no definite evidence respecting the barter system. But fortunately the Ancient Laws of Wales and Ireland afford us ample insight into the Keltic system. Irish tradition goes back far beyond the date at which the Brehon Laws were compiled, and from it we get a glimpse of a system almost Homeric: thus we read in the _Annals of the Four Masters_ under the year 106 A.D. that the tribute (_Boroimhe_, literally cow-tax) paid by the King of Leinster consisted in 150 cows, 150 swine, 150 couples of men and women in servitude, 150 girls and the king’s daughter in like servitude, 150 caldrons, with two passing large ones of the breadth and depth of five fists[50]. As this tradition makes no mention of payment in metals, but only of slaves, cattle and caldrons, which doubtless stood to one another in well defined relations, we need have no hesitation in assuming that the cow formed the chief unit of the earlier, as it did of the later Kelts. The Welsh naturally adopted the monetary system which sprang up after the reign of Constantine the Great in the Later Empire. Accordingly we find in certain of their Ancient Laws[51] tables giving in _denarii_, _solidi_ or _librae_ the values of various kinds of property. From these we can learn with accuracy the relations in value which existed between various kinds of property. Thus the calf from March (when the cows calved) to November was worth 6 _denarii_, to the following February 8 _den._, till May 10 _den._, till August of the second year 12, till November 14 _den._, till February 15 _den._, till February of the third year 28 _den._ The heifer is then in calf, her milk is worth 16 _den._ Thus the milch cow is worth 46 _den._, and up to August she is worth 48 _den._, up to November 50 _den._, and up to May of the fourth year is worth 60 _den._ A month’s milk is worth 4 _den._; a bull calf 6 _den._, the young ox when put to the plough is worth 28 _den._, when he can plough, 48 _den._, that is the same as the young milch cow of the same age; a gelding is worth 80 _den._, a farmer’s mare 60 _den._, a trained horse is worth half a _libra_; a bow with twelve arrows is worth 7 _denarii_ and an _obolus_; a queen bee (_modred af_) is worth 24 _den._, the first swarm 16 _den._, the second 12, the third 8; a foal is worth 18 _den._ to 24 _den._, a two year old 48 _den._, a three year old 96 _den._ A young male slave (_iuvenis captivus_) is worth 1 _libra_, a slave both young and of large stature (_captivus iuvenis et magnus_) is worth 1½ _libra_. It would appear that the Welsh, when taking over the Roman system, had adjusted their own highest barter-unit, the slave (probably female as