In the upper valley of the Arno stream there towers above the pines and giant beeches of the hills a great basalt rock, Alvernia, which looks over Italy, east and west, to the two seas.  That rock is accessible by but a single foot-track, and it is gashed and riven by grim chasms, yet withal great oaks and beech-trees flourish atop among the boulders, and there are drifts of fragrant wild flowers, and legions of birds and other wild creatures dwell there; and the lights and colours of heaven play about the rock, and the winds of heaven visit it with wholesome air.