Some look to holy books for hints, even gems; some to literature; others to the wiser scientists and statesmen. Philosophers on the hunt have always had the riddle like fragments of the Pre-Socratics, the tantalising remains brought to us care of the destruction of the great library at Alexandria. Strip away the details, the dust of subtle squabbles, and we recover at the core the worlds of Parmenides of Elea and Herakleitos of Ephesos. Their accounts offer two fundamentally incompatible outlooks; namely, that things all somehow comprise one and the same ever lasting structure, and that things, all of them, the structure included, change unendingly and irreversibly. Both outlooks have been re-visited many times. In our time, the ancient quarrels and insights re-surface in the question of sustainability which is yet another take on the irresolvable tension of trying to make sense of staying the course on that which cannot but change course.