Full disclosure: Professor Barney taught me Old English. His tools were a collection of notes, Mitchell and Robinson's Guide to Old English, Campbell's Old English Grammar, and his own Word Hoard. Of the three books, now that I can read Old English, Word Hoard is the one that is still fascinating to read. Barney took the most common words in Old English and discussed their meanings, where they came from, and what happened to them later (as with Old English gar, "spear"). If you are interested in Old English, this book is a must-have. If you are have ever been curious about how English has changed over the last 1,000 years, buy this book.