As I have repeated over and over again in this blog, Daniel Cassidy’s claims about Irish are almost entirely rubbish. His methodology consisted of finding phrases in English, deciding that they came from Irish, and then hunting through Irish (and/or Scottish Gaelic) dictionaries to find Irish equivalents. However, as there was hardly ever a satisfactory equivalent in the dictionaries, Cassidy put words together in ridiculous and unrealistic ways. According to his supporters, this doesn’t matter, because the Irish in 19th century slums supposedly forgot all their grammar and apparently stuck words together in random and incomprehensible ways.
Here’s a clear example of what Cassidy did. Suppose I am Cassidy and I decide that the phrase ‘My arse’ as an expression of scepticism at someone else’s words doesn’t come from the English words ‘my’ and ‘arse’. So I go to an Irish dictionary. I don’t actually speak any Irish, of course, and I’m not really sure about the pronunciation, but what the Hell! I’m Daniel Cassidy! I’m a genius! So, I find the word maith which means good or well, and which is pronounced mah or moy. So far, so good! Then I look for something which might go with it. Ah, there’s a word arsa, which means ‘said’.
So, if I put maith and arsa together, I get the ironic ‘Irish’ phrase maith arsa, which means ‘well said!’
Of course, this isn’t a real phrase, and it only makes sense if you pluck definitions for the component words randomly out of dictionaries. In Irish, the word arsa is limited in its use. It only ever occurs sandwiched between reported speech and the name of the person speaking. Almost all of the phrases in Cassidy’s book are like this, childish fakes based on misunderstood out-of-context dictionary entries which bear no relation at all to the genuine Irish language, a language of which Cassidy was totally ignorant.