But there are numerous exceptions to the rule. Often Rashi deems it necessary to state a definite solution, either because it has been the subject of controversies on the part of his masters, or because it was difficult to separate it from the rest of the discussion, or because it served as the point of departure for another discussion. Finally, the explanation of such and such a passage of the Talmud presupposes the solution of a question, unless the solution changes with the explanation of the passage. When the question is left in suspense by the Talmud, Rashi usually determines it in the strictest sense; but when it receives contradictory solutions, he either falls back upon analogous cases or adduces rules of Talmudic methodology. Often, however, his conclusion is nothing else than a statement of the practice observed in his time. In all these cases Rashi's authority carries great weight; so much so, in fact, as to overbalance that of Alfasi and Maimonides. Frequent appeal was made to it by casuists of a later date, and it would have been invoked still oftener had his Decisions been gathered together, like those of the Spanish and German rabbis, instead of having been scattered through a large number of compilations. * * * * * By reason of these and other qualities the Talmudic commentaries of Rashi without doubt outweigh his Biblical commentaries. I should be inclined flatly to contradict the opinion ascribed to Jacob Tam, Rashi's grandson: "So far as my grandfather's commentary on the Talmud is concerned, I might do as much, but it would not be in my power to undertake his commentary upon the Pentateuch." The Biblical commentary is not always absolutely sure and certain, and the defects are marked. The Talmudic commentary remains a model and indispensable guide. Although numerous Biblical commentaries have been composed with Rashi's as a standard and in order to replace it, no one has dared provide a substitute for his Talmudic commentary. From an historical point of view, the value of the Talmudic commentary is no less great. At the same period, in three countries, three works were composed which complemented one another and which came to form the basis of Talmudic studies. At the time when Rashi commented on the Talmud, Nathan ben Jehiel[121] composed the Talmudic lexicon, which is still used to a great extent, while Isaac Alfasi in his Halakot codified all the Talmudic regulations. Of the three works the first was the most celebrated. The exaggerated statement was made of Rashi, that "without him the Talmud would have remained a closed book."[122] And Menahem ben Zerah[123] said: "There was no one so illuminating, and so concise as Rashi in the commentary he wrote as if by Divine inspiration. Without him, the Babylonian Talmud would have been forgotten in Israel." The echo of this enthusiastic opinion is heard in the words of the Hebrew scholar H. L. Strack, a Christian, and the modern