21 “...These essays on the conceptual understanding of modern physics strike directly at some...”

22 “... essays in this volume which show how developments in the social sciences have affected the natural...”

23 “... are philosophers, it is worth noting that we have essays of philosophical significance here written by a...”

24 “...This collection of essays has evolved through the co-operative efforts, which began in the fall...”

25 “...'), much later collected with a splendid selection of his essays on philosophy of science, in English (1941...”