It is hard, in ordinary cases, to infer from such performances the exact degree of proficiency in the language which they should be presumed to indicate. Some translations are only the fruit of long and careful study.[341] On the contrary, there are instances on record in which excellent translations have been produced by persons possessing a very slight knowledge of the original. Thus Monte, the author of the best Italian translation of Homer, was utterly unacquainted with Greek;[342] Halley, without knowing a word of Arabic, was able to guess his way, (partly by mathematical reasoning, partly by the aid of a Latin version, which, however, only contained about one-tenth of the entire work,) through an Arabic translation of Apollonius _De Sectione Rationis_;[343] and M. Arnaud, the first French translator of Lalla Rookh, did not know a word of the English language.[344] But on all these points Mezzofanti’s fame is beyond suspicion. His translations, at least in his later life, were at once produced with the utmost freedom and rapidity, and are universally acknowledged to have been models of verbal correctness; and in most instances where the same passage is translated into many languages, the versions display a remarkable mastery over the peculiar forms and idioms of each. This wonderful success must be ascribed, no doubt, to his early and systematic exercise in translation, of which the specimen submitted to De Rossi is but one example. CHAPTER IV. [1807-1814.] The _Catalogue Raisonné_ of the Oriental and Greek manuscripts was not completed until 1807, having thus absorbed the greater part of Abate Mezzofanti’s time during two years. A large proportion of the Oriental MSS. had never even been entered upon the ordinary library catalogue, and no attempt at all had been made to describe them accurately, much less to register their character or contents. Very many of them too, as we learn from Mezzofanti’s letters, were imperfect; and a still more considerable number wanted at least the title and the name of the author. It was no trivial labour, therefore, to examine the entire collection; to decide on the name, the age, and the authorship of each; to describe their contents; and to reduce them all into their respective classes. For most of these particulars the compiler of the catalogue was utterly without a guide. It is true that Joseph Assemani’s catalogue of the Oriental MSS. of the Vatican, and the catalogue of those of the Medicean Library at Florence by his nephew Stephen Evodius, were in some cases available. But many of the Bologna MSS. are not to be found in either catalogue; and for all these Mezzofanti was of course compelled to rely altogether on his own lights.