Let no one argue against this that we are living in a different century, that much water has flowed under the bridge and that our problems are no longer the same. We are discussing living water which has not yet flowed away. We are familiar with enough historical examples, beginning with that of Spinoza, where men have worked ferociously to wall up for ever and bury deep in the earth sources which were made to quench their thirsts, but which their fear will not tolerate. For nearly a century academic philosophy has buried Marx in the earth of silence, the earth of the cemetery.