Books on Abraham Lincoln abound, with most of them told chronologically. They begin in Lincoln's youth, proceed through his early life, and culminate with his Civil War presidency and assassination.      In this book, however, there are twenty-six windows into the life of Abraham Lincoln and 26 windows into Mary Lincoln's life as well. They are just waiting to be opened. How you open them is up to you. Each page is packed full of information that immediately engages children (and adults!)      The pages may be read in alphabetical order, with each letter thoroughly describing an interesting episode in their lives. Or, read them chronologically, beginning with A for Abraham and Y for Mary.       Whichever way you choose to read this book, you will be opening not only a window but a doorway into the lives of one of the most beloved Presidents of the United States and one of the most interesting First Ladies.