he history of human thought had not started until a first abstraction came to the first thinker's mind.  A long-gone, nameless ancestor of ours suddenly realized that any simple and seemingly integral object, such as a tree before his eyes, can be broken into different aspects, and these aspects can be thought separately from the object itself---for instance, the tree's shape, size, density of leaves, smell in blossoming, etc.  An even more important discovery was that these aspects can be grouped together, categorized, compared or contrasted to those of other objects.  This might be called "philosophy" by some, but in fact this pattern of thinking forms the foundation of the most basic, mundane, even subconscious mental tasks that we perform literally every minute.

In fact, philosophy is also relevant in the history of abstraction; this branch of science (or is it a genre of art?) could only appear when our ability to analyze things became itself a subject of conscious analysis.  However, long before philosophy was able to emerge, the newly acquired power of abstraction had to find its expression in the human language.  Linguists know that many of the most primitive languages (found, for example, in primordial tribes) are characterized by their inability to express abstract or generalized ideas; such a language may have a single word for saying "falling snow" while lacking more basic words for "just snow" or "just falling."  Naturally, the inability to say something implies the inability to imagine it.

Interestingly, the history of abstract thought in general is an analog for the process of "abstracting out" the information essence from the presentation features of a document---the process which is one of the main subjects of this article.  It's not that the dichotomy of form and content was unknown in the past; it simply didn't offer anything useful for practical handling of documents, and therefore remained a purely philosophical speculation.  About the only "format conversion" possible in the pre-computer era was the one between written and spoken text (that is, reading a document out and writing it down), which posed little, if any, structural problems.

All this changed with the advent of computers.  Their diverse capabilities can be compared to the power of a well-developed human language; like a language, computers can represent and communicate any type of information by using complex notations, covering both content and presentation aspects.  Unlike language, however, computers need some assistance in performing these tasks---the notations they use must be developed by humans.  And not surprisingly, very early in the history of computerized document processing emerged the ideology of separating presentation from content.  Such a conscious philosophy was made possible (and necessary!) to "imagine" only because computers made it possible to "say" these two aspects discernibly.

Computers are not only a tool for expressing ideas, but also (and more importantly) for setting them to work.  That's how computers, probably for the first time in history, made philosophy an applied science.  It's difficult to imagine a real philosopher, even one who treats the distinction of form and content as commonplace, trying to apply these categories to some real-world documents, let alone developing a consistent notation for this purpose.  But this is exactly what technology architects have been doing for the last three decades---and now their work is going to be finally accepted by the widest possible audience of the Web.