Dickens and Gladstone, the Wordsworths and Virginia Woolf, there is a long list of greats who walked, not so much to reach work as in order to work. There is, in the connection with the physical world of setting one foot down in front of the other for miles at a time, a particular way of releasing mental energy that can amount almost to euphoria. The exertion of brisk movement, the need to monitor direction and the requirements of observation and safety, seem exactly calibrated to free up the brain so that it is sharper and clearer, better able to focus. But walking is more than that. In a world lived so extensively through the dislocating media of the web, where there is no reality, walking reconnects with real space and time. It is a way of rebuilding a relationship with the concrete, and it can also be a way of being free of it. Woolf called it street rambling. Dickens, more obsessive, houselessness. It's worth a try, even when there isn't a tube strike.