A classic I picked up from Science Fiction Bokhandeln in Stockholm.
I think Beagle was a philosopher at heart. I liked this passage:
"But the skull was laughing again… ‘Remember what I told you about time,’ it said. ‘When I was alive I believed—as you do—that time was at least as real and solid as myself, and probably more so. I said ‘one o’clock’ as though I could see it, and ‘Monday’ as thought I could find it on the map; and I let myself be hurried along from minute to minute, day to day, year to year, as though I were actually moving from one place to another." p.236