Reconstructing the evidence might be too hopeful because the conclusions would come from mere ignorance and be partially based on what we still do not know. From here we can only address the different types of evidence that piece together the very nature of the Celtic gods and goddesses, but the mixed and slightly unreliable evidence is certainly not easy to sort. .
The literary evidence for the existence of deities in Celtic religion is one source that reveals the character of the individual gods and goddesses. There exist two main bodies of literature evidence. One major body is vernacular written sources in Irish and Welsh. The most acknowledged Irish piece contains a collection of prose tales, known as the Ulster Cycle.2 Within these epic stories, the heroes swear not by God but by the gods of their tribes. However, many early mythic stories, such as the Irish Ulster Cycle, were not compiled until the medieval age. As a result, "Opinion is divided as to whether these texts contain substantial material derived from oral tradition or whether they were a creation of the medieval monastic authors" (Green 1997: 24). Other Irish stories frequently refer to the three goddesses of battle and death.3 These stories detail the nature of the gods and offer some explanation concerning their roles in Celtic society. Many stories that come down through Irish tradition make numerous references to "Lugh", whose Irish meaning is "shining light". This worldly god was worshipped by Celtic peoples in Ireland, Gaul and Spain.1 From its Irish translation, this god has been derived as a sun god, yet its precise nature is unknown. Other Irish references to Celtic deities include the "Book of Invasions" and the "History of Races".3 Regarding the mythological world as a whole, one Irish piece of work even suggests that gods were neither worshipped or sacrificed but were simply supernatural beings with magical powers.