The Greek word drus and the Sanskrit word druh both mean oak. The Indo-European root wid means to have knowledge of something. Either the Greek or the Sanskrit words can be combined with the Indo-European root to create a new word that means "knowledge of the oak". The new word is druid and the oak tree was, to the Druids, symbolic of life. The Celts were Druids. (1)
Aristotle, writing in 4th century BC, was the first to mention the druidic religion. Other Greek and Roman historians credit the Druids as having great knowledge in subjects as diverse as moral philosophy, natural science, Pythagorean calculations, astrology and geography. Cicero mentions their understanding of physics and astronomy and Pliny describes them as the doctors and healers with great knowledge of medicine. (2)
Julius Caesar wrote that Druids had knowledge of the stars and their motion and the size of the world and the earth. He admired their knowledge and organization. He also feared that organization and was afraid the Druids would unite the various clans. He felt that he could not have defeated a united Celtic army. Therefore, in the 2nd century BC, Caesar annihilated the druidic religion.
Druids were intellectuals and inquisitive by nature. They sought knowledge in everything. They also had to have extremely good memories. It was traditional to commit the entire Druidic teachings to memory and pass them on orally. Much of the druidic teachings were stated in verse to make them easier to remember. Even though they relied upon memory to pass on their beliefs, Druid priests were learned men. Many could read and write both Greek and Latin. (3)
Although called priests by Kevin Duffy in his book Who Were the Celts?, this may be an incorrect assumption. The classical writers have never referred to them as priests or priestesses. Being the intelligencia of the Celtic society, it is possible that some Druids acted as leaders in religious ceremonies, but as a class they do not appear to be priests. (4) They were the professional class: doctors, lawyers, teachers, philosophers, scientists, astronomers and inventors.
Interestingly, not all Celtic groups had Druids among them. Archeological digs in Turkey have found no evidence of Druidism among the Galatians who had settled there. (5)
Immortality was a major tenet of druidic belief. That they believed in life after death is evident in the supplies that were buried with their dead; supplies that would help them in the after-life. Jewelry, tools, weapons, horse bridals and tack, even chariots have been found in Celtic graves. One grave that was discovered near the town of Hochdorf in Germany contained an amazing variety of earthly objects. Included in the burial chamber was a four-wheeled cart. On the cart was a set of bronze dishes "- enough to accommodate nine people". Also found in the chamber were nine drinking horns. (6) Perhaps the deceased's attendants felt that he would be entertaining friends in the afterworld.
They may have buried horse equipment, but no evidence has been found to indicate that horses were buried. Perhaps, they believed that horses would be available in the after-life or, maybe, they just loved horses too much to sacrifice them that way.
Every society has had its religious holidays. The Celts were no different. There were four major celtic/druidic holidays throughout the year; one is still celebrated today. Imbolc was the feast of renewal and purification and was celebrated on 1 February. Beltaine was celebrated on 1 May by offering prayers for a bountiful harvest in the face of harsh northern weather. Almost every ancient religion had a feast or rite of fertility. The Celts were no exception. On 1 August, they celebrated Lugnasad, their festival of fertility. (7)
The fourth holiday is the one still celebrated today. Samain was dedicated to the gods of the underworld and the spirits of the dead. On 31 October, the spirits of the deceased would visit the living. Apparently, these spirits were not benign but would cause mischief if not appeased. The people would leave food outside the door for them in the hope that they would be satisfied and not harm the family inside. Today we celebrate it as Halloween and when children go from door to door asking for treats, they unknowingly, imitate the spirits the Celtic ancestors were trying to mollify. (8)
Over time even Halloween has changed. The Celts appeased demons and unfriendly spirits. Years ago the costumes worn by children were of ghosts, monsters and witches symbolizing the ghouls and evil spirits of the Celtic holiday. Only in recent years have children dressed up as princesses and super heroes and more benign characters.
When Christianity started to spread across the Middle East and Europe, the Celts were quick to accept the new religion. The Apostle Paul of Tarsus traveled widely in the Greek and Turkish area and converted many people. One group, the Galatians, was very close to Paul and became the recipient of one of his epistles which is now a book of the New Testament. (9)
Many think that Christianity suppressed the Druidic teachings. This is not so. Peter Ellis states that (10) The name Druid was given to many of the early saints who were Celtic. (11)