Digital technology has undeniably changed the meaning of "search" in the ecosystem of the library. Where speed and focus are the required attributes the digital catalog is a perfect tool. However there is another kind of search which also has value, and for which technology is less well adapted, a search which depends on serendipity and curiosity. One experience that is missing from online search is the discovery of the scope or breadth of a topic by encountering shelves and shelves of books about it many linear feet in size. It's true that virtual search makes the contents of those many shelves more accessible, but first we have to find out that they are there at all.
Another experience less well supported by digital search is the discovery that books have a context. Scanning the shelves for the title we seek we are brought close to other titles on the same topic. The topic is opened and enlarged for us, given more nuance and breadth. If it is a topic which has aroused our curiosity we find ourselves in a community among whom the same topic has been of crucial interest.
These are some of the aspects of a library search which Virtual Stack browsing enables. Another is to reproduce something a card catalog subject search provided, which was to list on the card what other subject headings a book might fall under. When you make a choice of a title in a Virtual Stack, a list of alternative subject headings appears.