For example, the 360 sculptured stones of Iona make one traveller (C. F. Gordon Cumming) think of the Kaaba at Mecca. ‘The Kaaba at Mecca (which to all good Mahomedans is as sacred as was the Holy of Holies to the Israelites) had, from time immemorial, been accounted by all the people of Arabia, to be the very portal of Heaven. Until the time of Mahomet, it was surrounded by 360 rude unsculptured monoliths , which, to the degenerate Arabs, had become objects of actual worship, and in presence of which, they were wont to sacrifice red cocks to the sun (just as the people in these Western Isles have continued to do, almost to the present day, though of course in ignorance of the original meaning of this ancestral custom).

‘More unflinching than the Christian reformers of Iona, Mahomet would admit of no compromise. Like the Synod of Argyll, he resolved on the destruction of these “monuments of idolatrie”, and so his iconoclastic followers did his bidding, and destroyed them utterly.

‘Nevertheless, he still allowed his converts to retain their custom of walking seven times in procession round the Kaaba itself, in reverence for Abraham and Ishmael, who had rebuilt it after the deluge, but he reversed the course of circuit.’

That Columba and his brethren, who built their little church of wood and its surrounding cells of wattle and daub, so that now nothing remains of their habitation, should also have reared these 360 stones is manifestly absurd, even had we no collateral aids to judgment, such as the remarkable twelve-stone circle, with its radiating lines, at Callanish in Lewis.

Moreover, until quite recent times, Highlanders spoke of Iona as the ‘Druid’s Isle’, and long after Columba had landed on it, the Irish continued to call it by that name.

One further thing has struck me, too, in this matter, and that is the obvious feeling of respect that these early Celtic missionaries had for the older faith. There was manifestly no bitter rancour, no outflowing of righteous wrath against a degenerate creed. As he made the cross on the monolith, so Columba in one of his written prayers calls Christ his Druid: ‘mo drui . . . mac Dé’ (My Druid . . . son of God).

As we stood there by the cairn, three oyster-catchers came crying against us for disturbing their peace, and as I watched the flash of the black and white plumage and the orange beaks, I remembered the wrong I had done to these servants of Bride or St. Bridgit. For once, long ago, while out hunting, I had shot two of them, and the man who had prompted me to do this carried them home to my landlady, who had been cook to a university professor in Edinburgh. She presented them browned on toast with the suggestion that the breasts only be eaten. They were very good.

In Gaelic they are known as gille-Brigde, the servant of Bride. And here again we are back among the old gods. I (or its variants) by which Iona is known to the ancient writers means The Isle. So the Hebrides are the Ey-Brides or the Isles of Brighit or Bridgit. This Brighit was a Druidic goddess, and, attended by noble vestals, her special care was the sacred fire. They had great reverence for fire in those days, and would hardly blow out a candle without a prayer that the light be given them again from heaven. They stuck to their sacred fire in the grove so obstinately that St. Patrick sent his convert, Bridgit, to deal with them. Now just as the Columban brotherhood found it more fruitful to bless than to attempt to destroy the standing stones, so Bridgit found it possible to convert these virgins only by allowing them to continue together in a community to look after what now became a Christian fire. And so it was done, and they were the first Christian community of women, and the temple of Bridgit at Kildare became a great convent.