Facts & origins · evidence layers
An alphabet is not automatically a calendar
The archaeological object, the medieval glossary and the modern birth sign belong to different centuries.
The stones
The National Museum of Ireland describes ogham as the earliest known form of writing in Ireland. Many surviving stones date from the fourth to sixth centuries and record personal names and kinship, often as memorials.
The letter lore
Medieval grammatical sources such as the Auraicept na n-Éces discuss ogham alphabets and letter names. Some later glosses associate letters with trees or plants, but even University College Cork's accessible twenty-letter teaching table differs from Graves at muin: bramble there, Vine in the calendar.
The missing step
No inscription or medieval tract in this panel assigns the thirteen selected letters to people by birth date. Graves supplied that calendar structure in the twentieth century.