This book is written by a philosopher for other philosophers and for that section of the reading public who buy in large quantities and, no doubt, devour with great earnestness the popular books written by scientists for their enlightenment. We common readers, to adapt a phrase from Samuel Johnson, are fitted neither to criticize physical theories not to decide what precisely are their implications. We are dependent upon the scientists for an exposition of those developments which - so we find them proclaiming - have important and far-reaching consequences for philosophy. Unfortunately, however, our popular expositors do not always serve us very well. The two who are most widely read in this country are Sir Arthur Eddington and Sir James Jeans. They are not always reliable guides. Their influence has been considerable upon the reading public, upon theologians, and upon preachers; they have even misled philosopher who should have known better. Accordingly, it has seemed to me to be worth while to examine in some detail the philosophical views that they have put forth and to criticize the grounds upon which these views are based.