The vale or strath of the Earn may best and simplest be said to extend from the head of Loch Earn along the course of the River Earn to its junction with the Tay, two and a quarter miles above Newburgh. The distance from top to bottom as the crow flies is about thirty-six miles, and the direction is very nearly due west and east. The valley may be sub-divided into four portions. The uppermost is Loch Earn itself, which is six and a half miles long and 306 feet above sea-level, so that the descent of the river in its thirty miles of course is not much. The surface of Loch Earn, James' Square in Crieff, and the Manse of Muthill, across the valley, are as nearly as possible on the same level. The Earn may be sectioned as follows:--From Loch Earn to the Bridge of Comrie; thence to the Bridge of Crieff; thence to the Bridge of Kinkell; thence to Bridge of Earn; thence to junction of Earn with Tay. For our present purpose we may stop near Forteviot, at the Earn boundary of the Presbytery of Auchterarder. Before we can rightly appreciate the more or most ancient Christian history of the Strath, we require to lay aside, and partly reverse, certain modern associations as to lines of travel. We think of Strathearn as running westward from Auchterarder, which lies on both the turnpike and railway route from Stirling to Perth. But in the days of our early Christianity it was mainly the sea on each coast that joined north and south of Scotland; whereas the more frequented routes were across country from west to east, because the west was then the seat of government and source of culture. Our early Christianity came from Ireland, and the route was by the Firth of Clyde, where Kintyre, Arran, Cumbrae, Bute, Kilmun, Dumbarton, Luss, and Balquhidder were all already provided with places of worship. The Vale of Leven and Loch Lomond were the natural approaches from the west to the upper end of Loch Earn and Strathearn. Another route connecting Perthshire with Iona was by Loch Etive, Dalmally, Tyndrum, and Glendochart. But the Leven and Loch Lomond route, judging by the saints to whom the oldest churches were dedicated, was the actual one usually traversed in reaching the valley of the Earn.