The Memex (never built) was to be a mechanized device that would enable the owner and user to consult all kinds of written material and organize it in any way the user wanted, adding private comments and linking documents together at will.
The Memex would store all written information on microfilm, so it could be kept in the user's desk. The desk would have several microfilm projectors, to enable the user to view several documents at the same time. (This is much like having windows on today's PCs and workstations.) The user could write comments and notes in the margin and have them scanned and added to the system.
The most important feature of the Memex would be the ability to create associative links between items or documents. Such links could be combined to form trails of information items, relevant to a certain topic. Such trails could then be photographed and mailed to other users for inclusion in their memex. Bush even forecast that building such trails could become a new profession, the "trail blazer".
Vannevar Bush was one of the pioneering scientists in the development of computers. (He invented the MIT Differential Analyzer in 1931.) He knew computers were very large and extremely costly machines. As such he could not envision Memex as possibly being a computer product.