I wonder how many of you have walked across cliffs and moors covered with purple heather and, in paying attention to where you’re putting your feet, noticed the way that the paths seem to change over time?  As people walk, furrows develop first through the plants and then through the soil in which they are rooted. Over time these furrows grow both deeper and wider as people start walking two abreast, or pass each other, or bypass puddles and muddy patches. Yet although the path grows and changes, fundamentally it remains the same—a way along which people go as they walk the same journey.