Boltzmann, Ludwig . . . the scientist asks not what are the currently most important questions, but “which are at present solvable?” or sometimes merely “in which can we make some small but genuine advance?” As long as the alchemists merely sought the philosopher’s stone and aimed at ﬁnding the art of making gold, all their endeavors were fruitless; it was only when people restricted themselves to seemingly less valuable questions that they created chemistry. Thus natural science appears completely to lose from sight the large and general questions.