Feet vs. shoes

When I stepped off the train tonight there was a girl walking ahead of me. Nothing unusual about that - except she wasn't wearing any shoes. I thought she'd quickly slip some flip flops on but no, she didn't and I saw that the soles of her feet were filthy. I suppose the pavements are quite clean really but I'd feel very vulnerable without shoes. I remember years ago walking to work I saw a tramp getting ready for the day, padding about in his stockinged feet on the pavement of Waterloo bridge. I was slightly freaked and then for a moment strangely jealous. It was cool to bump into my own thoughts so abruptly - why did I think it was so weird to not wear shoes on a nice warm day on a nice clean pavement?