From the history of Basque letters
http://www.basquexplorer.com/basqueletter/UsHist_1.htm
"....Fortunately the shape of characters in the Vascon - the old name for Basque - country was transmitted orally most of the time. This kind of character was inherited from the Roman invaders. By a trick of History, the global shape of the letters came to the Basque country, but how to carve them, without the needed tools?
At that time, the Basque engravers knew very little about the Roman ironworks technique; their rough tools couldn't carve deep characters like in the sculptures coming from Rome.
So, instead of carving deeply, they scraped the stone around the characters which thus stuck out, creating a new technique.
This explains why the Basque letters can hardly resist the passing of time: five-century-old engravings have eroded, for the most part."
NOTE: 'One doesn't need to cudgel one's brains to understand the obvious reason of vulnerability of raised letters', observes Yusuf ibn Aiyyoub, granite engraver to interviewer Scheherazade Shirazi, Art Historian.
'An engraved and deep niche has a wall around it for protection such as a deep dimple of one's navel. But if one is beset with a swollen bruise or a sore thumb we are extra careful, telling people who come too close, "Oh, mind my thumb or bruise . . . !"
'That's why I prefer carving deeper into the stone rather than doing raised letters. With a 9mm deep vertical cut such as the ones I do into granite I can guarantee erosion for at least three hundred years.
'However if you have a round the clock guard for the engraved work you'll need to arrange the vigilance for centuries . . .
'Raised script is reasonably safe only in an interior section of the premises, when it is affixed or mounted on a high wall, away from any impact, scraping or tampering. In the Masjid an-Nabawi raised calligraphy is quite safe although it is intalled on face or chest level for closer appreciation.
'The Turks prefer raised lettering, and many good calligraphic specimens have survived to this day. Being a very art conscious people, even the riff-raff among Turks have no urge to tamper or vandalise art work, and personal scores, if any, are settled in other ways. That's why there is no vigilance.'
