[Footnote 13:  Mr. Brewer has in most respects performed his work as editor in a satisfactory manner.  The many difficulties attending the deciphering of the text of ill-written manuscripts and the correction of the mistakes of ignorant scribes have been in great part overcome by his patience and skill.  Some passages of the text, however, require further revision.  The Introduction is valuable for its account of existing manuscripts, but its analysis of Bacon’s opinions is unsatisfactory.  Nor are the translations given in it always so accurate as they should be.  The analyses of the chapters in side-notes to the text are sometimes imperfect, and do not sufficiently represent the current of Bacon’s thought; and the volume stands in great need of a thorough Index.  This omission is hardly to be excused, and ought at once to be supplied in a separate publication.]

[Footnote 14:  This sum was a large one.  It appears that the necessaries of life were cheap and luxuries dear at Paris during the thirteenth century.  Thus, we are told, in the year 1226, a house sold for forty-six livres; another with a garden, near St. Eustache, sold for two hundred livres.  This sum was thought large, being estimated as equal to 16,400 francs at present.  Sixty livres were then about five thousand francs, or a thousand dollars.  Lodgings at this period varied from 5 to 17 livres the year.  An ox was worth 1 livre 10 sols; a sheep, 6 sols 3 deniers.  Bacon must at some period of his life have possessed money, for we find him speaking of having expended two thousand livres in the pursuit of learning.  If the comparative value assumed be correct, this sum represented between $30,000 and $40,000 of our currency.]

[Footnote 15:  Opus Tertium.  Cap. iii. pp. 15-17.]

[Footnote 16:  Opus Tertium.  Cap. xx. p. 65.]

[Footnote 17:  Opus Tertium.  Capp. xvi., xvii.  Roger Bacon’s urgency to the Pope to promote the works for the advancement of knowledge which were too great for private efforts bears a striking resemblance to the words addressed for the same end by his great successor, Lord Bacon, to James I.  “Et ideo patet,” says the Bacon of the thirteenth century, “quod scripta, principalia de sapientia philosophiae non possunt fieri ab uno homine, nec a pluribus, nisi manus praelatorum et principum juvent sapientes cum magna virtute.”  “Horum quos enumeravimus omnium defectuum remedia,” says the Bacon of the seventeenth century, “...opera sunt vere basilica; erga quae privati alicujus conatus et industria fere sic se habent ut Mercurius in bivio, qui digito potest in viam intendere, pedem inferre non potest.”—­De Aug.  Scient.  Lib.  II. Ad Regem Suum.