Ogham Stones are upright standing stones containing the earliest known indigenous Irish alphabet. Of unknown, (fully determinable) antiquity, this alphabet represents the earliest form of the Irish language. Their use continued well into the Christian era. Today, there are over four hundred surviving Ogham Stones with inscription in Ireland, as well as some examples in Britain (mainly Wales). The origin of the term 'Ogham' (pronounced 'om') is from the Irish “og-úaim” meaning 'cut with a sharp point'. This is also the same origin of the term 'Rune' which suggests something of an emotionality given to the markings as they were made. A kind of a 'magical' charging of the inscription rather than just recording a line of text.
This is a close up I took of an example in the National Museum of Ireland which illustrates the 'charged' nature of the incisions.