What then must be the age of lake dwellings, where three and even four superincumbent floors testify to the necessity of providing against the ever-rising water level! Lakes, marshes, and woods, have in all ages afforded shelter to the conquered, and have often enabled them to set the invader at defiance. Pliny describes the Caledonian forests as “Romanorum armis terminus.” A race inferior in numbers, in arms, or in physical development, would avail themselves of artificial or natural bulwarks to ward off the attacks of dreaded enemies, and water and woods have from the earliest times formed important factors in the art of defence. One cause to which may be ascribed the first erection of lake dwellings in Ireland was the original paucity of open country, for on the arrival of the first colonists (if credence is to be given to the early native annals) the only plain not covered with forest was the level district stretching between Dublin and Howth. This statement of the superabundance of forest is, to some extent, corroborated by the vast number of local names derived from Irish words signifying woods or timber of some description. However, the most probable cause of their erection was to serve as places of refuge, for these island homes would necessarily provide safety and protection; indeed such, in their later or historical existence, was undoubtedly the cause of their continuous occupation. It is quite obvious that in primitive times, especially, a habitation on water was of great security--more secure than could be a stockaded _doon_ or fort. Lake dwellings have been universally employed both in ancient and modern times: similar physical surroundings originated practically the same style of structures amongst far distant and even ocean-separated tribes. “Man is moulded to a remarkable degree, physically as well as mentally, by manner of living, food, and climate. Among barbarous nations,” says Humboldt, “we find a _tribal_, rather than an individual physiognomy; there are no varieties of intellectual development to stamp the face with diversity of character: thus the slave-dealers in Upper Egypt never ask for the individual character of a slave; they only inquire where he was born, his character being that of his tribe.” Let us now, like Puck, “Put a girdle round about the earth,”