Author: Julius Caesar, Gallic Wars 5.12-14 (link to Latin text and translation of the full work).
Comments: In a work primarily devoted to the Gauls (since Julius Caesar himself was a Roman general active in trying to subdue the Gauls), Caesar engages in a digression about the Britons in what is now England.
Source of the translation: H. J. Edwards, Caesar: the Gallic War, LCL (Cambridge, MA: Harvard University Press, 1917), public domain, adapted and modernized by Harland.
[Peoples of Britannia]
12 The inland part of Britannia is inhabited by peoples declared in their own tradition to be indigenous to the island, the maritime part by peoples that migrated at an earlier time from Belgica to seek booty by invasion. Nearly all the latter peoples are called after the names of the communities from which they sprang when they went to Britannia. After the invasion they settled there and began to till the fields. The population is innumerable. the farm-buildings are found very close together, being very like those of the Gauls [equivalent of what Greeks would call Celts]. There is great number of cattle. They use either bronze or gold coins, or instead of coined money tallies of iron of a certain standard of weight. In the midland districts of Britannia tin is produced, in the maritime iron, but of that there is only a small supply. the bronze they use is imported. There is timber of every kind, as in Gaul, except beech and pine timber. They think it’s wrong to eat hare, fowl, and goose. but these they keep for pastime or pleasure. The climate is more temperate than in Gaul, and the cold seasons more moderate.
13 The natural shape of the island is triangular, and one side lies opposite Gaul. On this side one angle, which is in Cantium [modern Kent] (where almost all the ships from Gaul come in to land), faces the east, and the lower angle faces south. This side stretches about five hundred miles. The second side heads towards Spain and the west, in which direction lies Hibernia [modern Ireland], smaller by one half, as it is thought, than Britannia. the sea‑passage is of equal length to that from Gaul to Britannia. Here in mid‑channel is an island called Monna [Isle of Mann]. in addition, several smaller islands are supposed to lie close to land, about which some have written that in midwinter night there lasts for thirty whole days. We could discover nothing about this by inquiries. but, by exact water measurements, we observed that the nights were shorter than on the mainland. The length of this side, according to the belief of the natives, is seven hundred miles. The third side heads northwards, and has no land confronting it. the angle, however, of that side faces on the way towards Germania. The side is supposed to be eight hundred miles long. So the whole island is two thousand miles in circumference.
14 Of all the Britons the inhabitants of Cantium, an entirely maritime district, are by far the most humanized (humanissima; i.e. civilized), differing only a little from the manner of life of the Gauls. Regarding those further inland, most do not sow grains, but live on milk and flesh and clothe themselves in skins. In fact, all the Britons dye themselves with woad flower, which produces a blue colour, and makes their appearance in battle more terrible. They wear long hair and shave every part of the body except the head and the upper lip. Groups of ten or twelve men have wives together in common, and particularly brothers along with brothers, and fathers with sons. but the children born of the unions are considered to belong to the particular house to which the maiden was first led.