I dreamt that I was trying to figure out how much would the underground system in London cost today by comparison with its cost in the Nineteenth Century, when most of it was built. I do not remember much of the dream except that my attempts to come up with a firm figure were thwarted by all sorts of problems. Among other things, my ballpoint pen would not write, and I could not find another one. I also remember drawing cross-sections through different underground lines around the city together with sewers, water pipes, and other conduits. I felt almost angry with myself when I woke up in the middle of the night. What a silly dream. To begin with, why compare the two costs? In addition to all sorts of technical problems due to discounting and inflation, the figure would be rather pointless. On top of that, how could I be so incompetent in my calculations? I would expect some prowess after so many years in building or construction economics. Much more important, why spend my nights comparing costs even if I had a good reason for the exercise? There are so many other things to dream about! Luckily, I fell asleep again soon enough. The dream struck me as merely funny in the morning. There is a soft spot in my heart for the London underground.