The Celtic tenants also paid military service to their superiors. The
remotest kinsmen of each lord of land, poor as they might be, were valued
for their swords, and were billeted on the unfree or servile tenants, who
gave them free quarters.

In the feudal system of western Europe these old traditional customs had
long been modified and stereotyped by written charters. The King gave
gifts of land to his kinsmen or officers, who were bound to be "faithful"
(_fideles_); in return the inferior did homage, while he received
protection. From grade to grade of rank and wealth each inferior did
homage to and received protection from his superior, who was also his
judge. In this process, what had been the Celtic tribe became the new
"thanage"; the Celtic king (_righ_) of the tribe became the thane; the
province or group of tribes (say Moray) became the earldom; the Celtic
Mormaer of the province became the earl; and the Crown appointed _vice-
comites_, sub-earls, that is sheriffs, who administered the King's
justice in the earldom.

But there were regions, notably the west Highlands and isles, where the
new system penetrated slowly and with difficulty through a mountainous
and almost townless land. The law, and written leases, "came slowly up
that way."

Under David, where his rule extended, society was divided broadly into
three classes--Nobles, Free, Unfree. All holders of "a Knight's fee," or
part of one, holding by _free_ service, hereditarily, and by charter,
constituted the _communitas_ of the realm (we are to hear of the
_communitas_ later), and were free, noble, or gentle,--men of coat
armour. The "ignoble," "not noble," men with no charter from the Crown,
or Earl, Thane, or Church, were, if lease-holders, though not "noble,"