Then came the journey up to London through Birmingham and the Black District, another lesson, which needed much more to be rightly felt. The plunge into darkness lurid with flames; the sense of unknown horror in this weird gloom which then existed nowhere else, and never had existed before, except in volcanic craters; the violent contrast between this dense, smoky, impenetrable darkness, and the soft green charm that one glided into, as one emerged - the revelation of an unknown society of the pit - made a boy uncomfortable, though he had no idea that Karl Marx was standing there waiting for him, and that sooner or later the process of education would have to deal with Karl Marx much more than with Professor Bowen of Harvard College or his Satanic free-trade majesty John Stuart Mill.