Amazon is great at helping you find what you are looking for, but isn't good at showing you what to look for. That's what a bookshelf does. I heard on NPR the other day concerns with the internet creating our own insular networks, where our viewing histories and purchases dictate the products and information we are exposed to. The large danger there is how it blocks off ideas that are beyond your purchasing history, and only allows through those that further solidify your previously held beliefs.
One way to combat this is to go after the new Google search engine coding, but it is also to support local book stores. Book shelves are a great way to go beyond your own ideas and "purchasing history". Now, I almost always end up going to European History and Philosophy sections in book stores, and given the predominant cataloging method in place, those topics are almost always sorted next to the same other topics, but still, you are most definitely exposed to works from within and without your "purchasing history", and in my mind, are more likely to leave with something that expands your understanding.
After those two hours, I left with a History of Rome from the late 19th century, a History of "Modern Europe" spanning 1830-1914, a book on the problems of philosophy, and finally - the one from outside my purchasing history - the Three Musketeers, all in French.
I've got a lot of reading to do :) and another used book store I just found: Mecosta Book Gallery
