Now in researches of this kind the liability to blunder is so great, and many able writers have blundered so egregiously, that the inquiry ought not to be entered upon without due preparation, and should not be continued without constant exercise of the most scrupulous caution. The great danger of being betrayed into error by the plausibilities of phonetic etymology should never for a moment be lost sight of. Where possible, the earliest form of the name should be recovered, for in the course of time local names are apt to be so corrupted as to lose all obvious trace of their original orthography. The Celtic place-names[6] are as a whole singularly descriptive. The Celtic tribes, indeed, have manifested, in that respect, a keener appreciation of landscape and a more poetical eye for nature than their Saxon successors. Who that has ever stood beneath the sombre shadow of the cloud that so often rests on the shoulder of the Grampians will fail to recognise the peculiar fitness of the Gaelic name for the highest summit of the chain--Ben-na-muig-dubh, 'the mountain of dark gloom'? Or who has ever watched the Atlantic billows bursting into white foam against the cliffs of Ardnamurchan and did not acknowledge that only a poetic race could have named the place 'the headland of the great ocean.' The colours of mountain and river have been seized upon by these people as descriptive characters that have suggested local names. Swiftness and sluggishness of flow have furnished discriminating epithets for streams. Moors, forests, woodlands, copses, groups of trees, solitary bushes, lakes, mosses, cliffs, gullies, even single boulders, have received names which record features in the landscape that struck the imagination of the old Celt, and which are still in use, even when the features that suggested them have long vanished out of sight. From this source glimpses may be had of the character of the vegetation and of the wild animals in prehistoric times. Thus we learn that the desolate, treeless tract of Ross-shire known as the Dirriemore (great wood) must once have been clothed with forest. How numerous wild boars were in the country is shown by the frequent occurrence of the name of the animal (Torc, turk) in local topography. The former haunts of the wolf are indicated by its Gaelic appellation (madah, maddie) in Highland place-names. Many descriptive names which have never found a place on any map are well known to the Welsh and Gaelic-speaking inhabitants, who in the more mountainous and trackless regions have often a wonderful acquaintance with the details of the topography.