Most people forget that leather is an organic material and will slowly decay over the years and must be taken care of. For the older books that have become scuffed and have wear, one should apply a good leather dye of color that blends and let dry for a day or two. Then give it a thin coat of lanolin and rub it in well, vasoline will work also but is more messy and harder to work with, but when you are done the book will look like new. Lanolin should be applied ever couple of months to keep the book in good condition. All leather cover books you have should have the lanolin treatment ever six months to preserve them.