Much has been said of their human sacrifices in colossal images of wicker-work--the "_immani magnitudine simulacra_" of Caesar--which were filled with human victims, and which crackled and disappeared in towering flame and columns of smoke, amid the loud chantings of the bards.

The most that can be said in palliation of this custom is, that almost always such a scene presented the judicial execution of criminals, invested with the solemnities of religion.
In their theology, _Esus_, the God Force--the Eternal Father--has for his agents the personification of spiritual light, of immortality, of nature, and of heroism; _Camul_ was the war-god; _Tarann_ the thunder-god; _Heol_, the king of the sun, who inflames the soldier's heart, and gives vitality to the corn and the grape.[4] But Druidism, which left its monuments like Stonehenge, and its strong traces in English life, now especially found in Wales and other mountainous parts of the kingdom, has not left any written record.
ROMAN WRITERS .-- Of the Roman occupancy we have Roman and Greek accounts, many of them by those who took part in the doings of the time.

Among the principal writers are _Julius Caesar_, _Tacitus_, _Diodorus Siculus_, _Strabo_, and _Suetonius_.
PSALTER OF CASHEL .-- Of the later Celtic efforts, almost all are in Latin: the oldest Irish work extant is called the _Psalter of Cashel_, which is a compilation of the songs of the early bards, and of metrical legends, made in the ninth century by _Cormac Mac Culinan_, who claimed to be King of Munster and Bishop of Cashel.
THE WELSH TRIADS .-- The next of the important Celtic remains is called _The Welsh Triads_, an early but progressive work of the Cymbric Celts.

Some of the triads are of very early date, and others of a much later period.

The work is said to have been compiled in its present form by _Caradoc of Nantgarvan_ and _Jevan Brecha_, in the thirteenth century.