The mysterious Cathbad was the Druid to King Conor MacNessa of Ulster who served not only as his advisor but also eventually as a means of checking the excessive use of power by the King.

The word Druid can mean 'oak knower' or 'oak seer' and Druids were often seen as members of an exclusive occupational class, and also as sorcerers. It is generally accepted that the Druid was a type of intermediary, a conduit to the Otherworld.

The centre of a Druidic ritual was in a sacred place located close to trees. The favorite trees of the Druids were the Oak trees and the Rowan trees and it was on wattles of this tree that a Druid would sleep to gain prophetic visions from their dreams.

A Druid's opinion was always sought on matters of law and tradition. They could identify wrong-doers, interpret dreams, cure illnesses and give shrewd military advice. While the Druid was believed to possess mystical powers they should not be confused with 'the bard' who was more often a leading figure such as a poet whose verse was believed to have magical connotations. The teachings of the Druid were based on the five elements: earth, sea, sky, sun and moon.

Cathbad held the highest office at the Court of King Conor MacNessa. As was the tradition at the time no one was permitted to speak before the King, but even the King himself waited to hear first from Cathbad!

Cathbad's prophecies are pivotal in many of the stories of that ancient time such as the occasion when Cuchulainn took up arms after Cathbad predicted that anyone to do so for the first time on that day would live a memorable, albeit short life. Immediately the boy hero Cuchulainn took up arms and slay three champions who had long dominated Ulster, instantly becoming a hero.

It was also Cathbad's prophecy about Deirdre of the Sorrows that sets in motion her tragic tale.

When Deirdre was born, Cathbad was able to see from the cry she gave when she was still in the womb that she would bring death and destruction after her. Conor MacNessa tried to avert this prophecy, but his pride and jealousy was so great that he could not let Deirdre go, as a grown woman, to be with the man she loved, Naoise. After luring Deirdre and the sons of Ushnu back to Ulster under a false promise of peace, the King enlisted Cathbad's help in subduing the fearsome brothers.

Cathbad agreed to help, only on condition that Conor not kill the sons of Ushnu. Cathbad surrounded the warriors with a spell that made them feel as if they were enveloped by water. They had to swim until their arms were so tired that they dropped their weapons. The King then seized his chance and had the brothers executed, keeping the letter of his promise by having someone else actually despatch them from the mortal realm.

Cathbad was furious at the King's misuse of his powers and put a curse on Conor MacNessa: that his line would end with him, and he would have no descendants after him. This was a terrible curse in a culture that prized a person's legacy and lineage.

King Conor MacNessa was proud though and thought himself safe, having many sons. But he underestimated the power of the Druid's curse and over the course of his life, one by one, all his sons died, and by the time he was an old man only the exile Cormac Cond Longas still survived, living in Connaught. The King asked Cormac to come back to Ulster to succeed him. Cormac agreed and set out on his journey to meet his father, only for a deadly accident to befall him on the way, fulfilling Cathbad's curse.

Other legends of Cathbad have it that the Druid Cathbad was in fact the father of King Conor MacNessa, making the curse he placed upon him even more sinister. It is told that the Princess Nessa had consulted with Cathbad, enquiring of him what that particular day would be suited to. He answered:

'This day is auspicious for begetting a King upon a Queen!'

His meaning was clear and he lay with Nessa begetting the son Conchobar, later known as Conor, who would become the King of all Ulster.

Cathbad is the quintessential Druid of Irish mythology. The relationship between the King and Druid was of extreme importance, for it determined the fortune of the King and that of his people.

If there was a good King there was seen to be good corn and meat and therefore prosperity for the people. Thus the Druid represents the child of wisdom, born of the male sun representing the cult of the King with mother earth symbolized by the female Goddess. Despite possessing great knowledge, a Druid also held great power. Not only did Druids serve a high king, but they also curtailed the power of that ruler.

This was especially true in the tales of Cathbad and King Conor MacNessa with some tellings having it that Cathbad cursed his very own son, thus ending the line of Conor MacNessa, the great King of Ulster.