All over Ireland there are wishing-stones of one type or another, and every one of them has some sort of condition that you have to fulfil before you get your wish.
In Glendalough you must be able to make your arms reach right around the wishing cross; in Killiney, as far as I remember, you have to walk right around the obelisk one way to the top and then turn around and walk down the opposite direction.
In Avoca the Motto Stone has, I think, the most delightful condition of all. You must walk three times around it without thinking of a goat, climb up on top of it and wish. Considering that the countryside is literally crawling with goats of all shapes and sizes, the chances of forgetting them are pretty slim, and, besides, the act of remembering what not to think of is enough to put goats unshakeably into your mind.
It rather reminds me of the old idea of seeing a piebald horse and remembering not to think of his tail. I have never seen a piebald horse yet that his tail was not the most prominent part of his anatomy.
The Irish Times, June 14th, 1941