The ancient Druids were said by J. Caesar to take up to 21 years to train one of their number. It is reasonable to suppose that this training included the basic literacy and numeracy which, until recently, was taken for granted in higher students.
It is fair to say that Druidical books are few, perhaps reflecting the Celtic oral culture, perhaps also demonstrating that Druids tend to reject dogma. It would be quite wrong to suggest that any book on Druidry is fully authoritative, there being controversy among scholars on numerous points.
Because many of the Druidical sources are long out of copyright, they are often available online. The Celtic section of sacred-texts.com includes most of the valuable ones, such as the Barddas and the unsettling prophecies of the Brahan Seer. More links are given in Reference Links.
More recently published works (some regrettably out of print) likely to be of interest include:
Strongly recommended; a definitive work on tree-lore. An abridged field version, A tree in your pocket (Thorsons, 1998; ISBN 0722537786), is also available.
Essential reading but difficult, controversial and more than 500 pages long, this is Graves' personal interpretation of European mythology, and includes a version of the tree-Ogham which differs from that commonly used.
Regrettably difficult to obtain, this is an important work but in many ways as personal an interpretation as that of Graves, some of Nichols' theoretical conclusions being not uncontroversial.
A fine and comprehensive work, concentrating to some extent on the co-existence of Druidism and early Christianity. Recommended.
A fascinating and scholarly history of the development of the modern Druid movement, by a major contributor to it.
Transatlantic in style (despite Nick Mann being based in Glastonbury), this Druidry DIY book contains a number of magickal procedures which have been found startlingly effective.
Not a book about Druidry but the final masterpiece of a great Celtic word-wizard. The ultimate expression of the labyrinthine complexity of the Celtic mind.
"Here words are not the polite contortions of twentieth-century printer's ink. They are alive." Beckett
May there be peace in the East
May there be peace in the South
May there be peace in the West
May there be peace in the North
May there be peace throughout
the whole world