I've been singing and playing folkmusic for almost 50 years and have many, many books of songs, including one I made myself with tons of lyrics, but no chords or music. I never forget a tune or how to play it, but have always had trouble with lyrics. Now as the years pass me by, if I don't use the books I don't sing the songs. I just have too much of a memory problem. Mind you, I wouldn't pay a nickel to see a performer who had to use a book on stage. If his memory is that bad, he should do like I do and just play for himself and his friends.