Sâyana quotes a number of Sanskrit works which, at the time when I began my edition, had not yet been edited. Such were the Nirukta, the glossary of the Rig-veda; the Aitareya-brâhmana, a very old explanation of the Vedic sacrifice; the Âsvalâyana Sûtras, on the ceremonial; and sundry works of the same character. Sâyana generally alludes very briefly only to these works and presupposes that they are known to us, so that a short reference would suffice for his purposes. To find such references and to understand them required, however, not only that I should copy these works, which I did, but that I should make indices and thus be able to find the place of the passages to which he alluded. This I did also, but over and over again was I stopped by some short enigmatical reference to Pânini’s grammar or Yaska’s glossary, which I could not identify. All these references are now added to my edition, and those who will look them up in the originals, will see what kind of work it was which I had to do before a single line of my edition could be printed. How often was I in perfect despair, because there was some allusion in Sâyana which I could not make out, and which no other Sanskrit scholar, not even Burnouf or Wilson, could help me to clear up. It often took me whole days, nay, weeks, before I saw light. A good deal of the commentary was easy enough. It was like marching on the high road, when suddenly there rises a fortress that has to be taken before any further advance is to be thought of. In the purely mechanical part other men could and did help me. But whenever any real difficulty arose, I had to face it by myself, though after a time I gladly acknowledged that here, too, their advice was often valuable to me. In fact I found, and all my assistants seemed to have found out the same, that if they were useful to me, the work they did for me was useful to them, and I am proud to say that nearly all of them have afterwards risen to great prominence in Sanskrit scholarship. From time to time I also worked at interpreting and translating some of the Vedic hymns, though I had always hoped that this part of the work would be taken up by other scholars.