This is the entry in his journal:—­“See frequently on the road-sides small verdant hillocks, styled by the common people shi an (sithean), or the Fairy-haunt, because here, say they, the fairies, who love not the glare of day, make their retreat after the celebration of their nocturnal revels."[53] Now, as the “Picts’ houses” are, to outward appearance, “small verdant hillocks,” the parallel is very exact.  With these two references compare also the mention, in a quaint old gazetteer printed at Cambridge in 1693,[54] of the tribe of the “Germara,” defined as “a people of the Celtae, who in the day-time cannot see.”  Although the author usually gives the sources of his information, in this instance he gives none.  But the statement agrees perfectly with the belief found everywhere throughout Northern Europe that “the dwarfs could not bear daylight, and during the day hid in their holes."[55] It really seems impossible to avoid the inference that all this was perfectly true.  When Leif went down into the underground house in Ireland, he could not see at first, though at length he saw in the obscurity the glimmer of his opponent’s sword.  Consequently, the denizens and builders of these subterranean retreats must either have had something very like “cat’s eyes,” or else they must in general have had numerous lamps burning.  This will be understood by an examination of one or two of the accompanying diagrams.  It seems to me beyond question that a people living this underground life must have differed very distinctly from ourselves in the matter of vision; and to them the brightness of noonday must have been blinding.  This physical fact—­if it be a fact—­would explain much that is otherwise strange and incredible in the traditions relating to the Picts—­or Pechts, as they were formerly called in Scotland.  However, it is sufficient for my present purpose to note that this peculiarity associates, and indeed identifies, the Picts with the dwarfs or fairies of tradition.

Having thus shown that Fians, Fairies, and Picts are so closely associated as to be, in some aspects, almost indistinguishable from one another, I shall now refer to the structures which are popularly believed to have been their dwellings.  Some of these are wholly underground, others partly so, and others quite above ground.  In many other ways, also, they vary.  But all of them are unquestionably links in one special style of structure; of which the most marked feature, or at any rate that which is common to all, is the use of what is called the “cyclopean” arch.  This is formed by the overlapping of the stones in the wall until they almost meet at the dome or apex of the building, when a heavy “keystone” completes this rude arch.  The principle of the arch proper was obviously quite unknown to the originators of such structures.