That line in the sand

Chris Walley, over at News from Farholme (check out his Lamb Among the Stars series as well - its pretty awesome) just put up a post about how, in many areas of life, we draw a line in the sand, and keep thinking everything is ok, as long as that line isn't crossed, and we live with our heads in the sand sometimes (yes, I know, that's one sand metaphor too many - Dr. Walley is a professional author, I am not). Here's an excerpt:
In a complex world it is easy over issues of concern to mark a line in the sand at some particular point. You turn your attention elsewhere, constantly glancing back at your line in the sand and, as long as it remains untouched, you conclude that all is well. So, for example, I consider that everything is all right as long as I can walk down to the city centre in daylight without being mugged. There are many such benchmarks in society and in our lives. Indeed I suspect almost all our public and private morality is composed of a series of such benchmarks.