I found incredible kindness, dignity and hospitality in both Iraq and Afghanistan - am only alive because of it - the most worthwhile lesson of a twenty month walk to these countries was a deepening appreciation of the kindness of strangers.

I left things out - my motivations, my history, my emotional responses - because I am not good at understanding them or writing about them. I tried and it was generally boring and always unconvincing. Most importantly I wanted to try to place Afghans and Afghanistan in the foreground rather than my own character.

I'd like to come back to the West eventually. In the end abroad I am always a stranger, active politics in particular is not accessible to me and although people are generous, I can never be on the inside of a culture that relies a great deal on the private space and the family.

In the mountains, travelers were reduced to the speed of men on foot. Here, the ancient English sense of journey, 'a day's travel' (French journee), meant the same as the Old Persian word farsang, 'the distance a man could travel on foot in a day,' and the territory was in effect ungovernable.

I had been walking one afternoon in Scotland and thought: Why don't I just keep going? There was, I said, a magic in leaving a line of footprints stretching across Asia.

This idea that failure is not an option: It makes failure invisible, inconceivable and inevitable.

The question shouldn't be what we ought to do, but what we can do.