My post of 29 february contains a paraphrased quote from Máire Ní Chathasaigh; my conscience prompts me to contribute the exact quote.

No other instrument symbolises both the continuities and discontinuities of the Irish music tradition so thoroughly. It is the oldest instrument within it, having been played here for more than a thousand years, and therefore the one which appears to have changed the most.
page 173, The Companion to Irish Traditional Music (only the article titled "Harp")