Commenta Bernensia
One of the most prominent examples of this threefold death in three separate sacrifices comes to us from Lucan In his epic poem, Pharsalia, which relates Caesar's conquest of Gaul, he describes a set of three Celtic gods who receive human sacrifices: et quibus inmitis placatur sanguine diro/ Teutates horrensque feris altaribus Esus/ et Taranis Scythicae non mitior ara Dianae. ("To whom they appease with cruel blood, harsh Teutates, and wild, bristling Esus, and Taranis whose altar is as insatiable as that of Scythian Diana.")
One of the marginal notes in a 10th-century manuscript of the Pharsalia, known as the Commenta Bernensia is highly important for an understanding of how these lines relate to Proto-Indo-European culture. “The later... scholiasts... elaborate on Lucan: they elicit the information that Taranis was propitiated by burning, Teutates by drowning, and Esus by means of suspending his victims from trees and ritually wounding them” This scholium is of huge significance to understanding whether this text contains evidence of the threefold death in Celtic worship. It is a distinctive detail, and it matches closely with numerous other details that relate to ritual practice in Indo-European society.
In recent years an Indo-European pattern of threefold death has been identified and discussed in terms of this tripartite ideology by a number of followers of Dumezil... The pattern is found in myths and legends of various Indo-European peoples in two main forms. The first of these is a series or grouping of three deaths, each by a different means. The second is a single death by three different means simultaneously.
Evans goes on to cite numerous stories from various Indo-European society. All of these stories he tells contain this theme of a tripartite death. He argues, following Dumezil, that three distinct methods of sacrifice, corresponding to the three functional deities, was an important Proto-Indo-European ritual.
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