"Inferior to its predecessors in the importance of its scientific details and the illustration it supplies of Bacon's philosophy, it is more interesting than either, for the insight it affords of his labors, and of the numerous obstacles he had to contend with in the execution of his work. The first twenty chapters detail various anecdotes of Bacon's personal history, his opinions on the state of education, the impediments thrown in his way by the ignorance, the prejudices, the contempt, the carelessness, the indifference of his contemporaries. From the twentieth chapter to the close of the volume he pursues the thread of the Opus Majus, supplying what he had there omitted, correcting and explaining what had been less clearly or correctly expressed in that or in the Opus Minus. In Chapter LII. he apologizes for diverging from the strict line he had originally marked out, by inserting in the ten preceding chapters his opinions on three abstruse subjects, Vacuum, Motion, and Space, mainly in regard to their spiritual significance. 'As these questions,' he says,' are very perplexing and difficult, I thought I would record what I had to say about them in some one of my works. In the Opus Majus and Opus Minus I had not studied them sufficiently to prevail on myself to commit my thoughts about them to writing; and I was glad to omit them, owing to the length of those works, and because I was much hurried in their composition.' From the fifty-second chapter to the close of the volume he adheres to his subject without further digression, but with so much vigor of thought and freshness of observations, that, like the Opus Minus, the Opus Tertium may be fairly considered an independent work."--pp. xliv-xlv.[13] The details which Bacon gives of his personal history are of special interest as throwing light upon the habits of life of a scholar in the thirteenth century. Their autobiographic charm is increased by their novelty, for they give a view of ways of life of which but few particulars have been handed down. Excusing himself for the delay which had occurred, after the reception of the Pope's letter, before the transmission of the writings he had desired, Bacon says that he was strictly prohibited by a rule of his Order from communicating to others any writing made by one of its members, under penalty of loss of the book, and a diet for many days of bread and water. Moreover, a fair copy could not be made, supposing that he succeeded in writing, except by scribes outside of the Order; and they might transcribe either for themselves or others, and through their dishonesty it very often happened that books were divulged at Paris.