The Weekly Review says: "The plan of the work is to give formal essays on some of the important divisions of the subject, followed by philosophical discussions in the form of dialogues. Under one aspect the movement of the fourteenth and following centuries in Southern Europe was a revival of paganism. The lights of the Church occupied themselves with Latin and Greek writers instead of with the Fathers. This eager study of the classics could not fail to loosen the bands of bigotry a little. Men could not read Ciceo for his style merely and not get some contact with his ideas. The ideas may not be very valuable intrinsically, but they were different from those of Italian readers of the thirteenth century. Another cause for the emancipation of the intellect was the contact with a civilization, in many respects higher, brought about by the Crusades. Still another cause is to be found in the dissensions between Pope and Kaiser, between the spiritual and secular powers, and still more in the intestine divisions of the Papacy itself.
"The longest and on the whole most interesting essays are those on Giordano Bruno and Vanini; partly perhaps, at least in the case of the former, owing to the vigor of thought, partly on account of the tragical death of the thinkers discussed."
The London Athenaum concludes a lengthy review with the words: "The most characteristic featuie of the book, it may be noted in conclusion, is the account given of anticipations of the Renaissance in the Middle Ages. Anticipations of later thought in the Renaissance itself are less dwelt on. What is sometimes called the 'transition period' is, for the author, a last term. In the distinctively modern development of philosophy he seems to be less interested. In spite of his stress on 'skeptical' inquiry, it is each thinker's conception of the universe as a whole that he cares about rather than his critical scrutiny of the principles of knowledge. This last inquiry, as has often been said, is more distinctively modern. What distinguishes the Renaissance is the effort to attain again a comprehensive theory of the universe. The result might at the time be disintegrating rather than reconstructive; but the effort itself, as Mr. Owen sees clearly enough in the case of Bruno, was one of synthesis more than of analysis."
-Book Reviews, Vol. 1