I like this definition of a book (which I found in a Times Literary Supplement essay):
I. A. Richards called the book “a machine to think with” . . .
Notice that the definition has the two elements that Aristotle said were necessary to get a handle on a thing—a book is among the genus of machines and its differentia (diaphora) or species (what makes it unique among machines) is that it aids thinking.
But there are other machines that aid thinking (such as a pocket calculator, a DVD player, an iPad, a scroll, a grocery list, a Rolodex, a string tied about the finger for memory, etc), and so the differentia is, arguably, not entirely serviceable, not quite specific (species) enough.
So how about an alternative genus-species definition like the following:
The book is a recall machine of paper and ink pages spinal bound.
This covers, by far, the vast majority of books. (It’s conceivable that a book could be written in, say, blood on pages of leather—and perhaps this has been done—but certainly not often.) But it’s not quite as elegant somehow as I. A. Richards’ looser definition, and it lacks his key verb to think (though it is implied in recall). Indeed, my definition shifts the emphasis, in the differentia, away from its role in assisting thought and onto its unique medium (spinal bound paper and ink).
So let’s try again. What is a book?
A book records the buildup of an author’s organized thoughts and preserves them for others to reflect on and to think even further with. So it’s a device for resisting entropy (the loss of information) and time.
But other devices do the same thing (such as a voice recorder with a play back function). So it would seem that any precise definition of a book that includes Aristotle’s genus and species markers necessarily forces one to shift from its purpose (in the genus) to its unique medium (in the species).
But if we go back to the book as having something to do with resisting entropy (a thought I like), suddenly it takes on the quality of being alive: a book is like a cell; it’s a medium for preserving a buildup of information, and can function as the springboard for still further iterations of information (what I. A. Richards captures in his definition—the book as a machine for assisting the reader’s further thought).
So there are two ways to define something: you can do so by way of analogy or by way of the precision of Aristotle’s genus-species designations.
But wait. Aren’t all methods of definition—even Aristotle’s—a way of framing a thing by metaphor, simile, analogy? What is the sentence—A book is a machine.—but a metaphor?
So why not say that a book really is DNA—the DNA of civilization? Is it because the analogy is not perfect? Not perfect in what sense? Aren’t a book and a DNA molecule doing the exact same thing—preserving information for something external to them to read? In the case of DNA it’s the transcriptors in the cell that read it; in the case of the book, it’s the conscious human eye. And isn’t it interesting that both DNA and the book have a spinal quality (information linked about a spinal appearing structure)?
So just as the book is central to civilization, DNA is central to the functioning of the city of the cell. If there wasn’t something doing the work of the book, our civilization would fall apart; likewise, life in the absence of the repository of its memories—it’s DNA—would fall apart too.
So let’s try a genus-species definition with the book as a central component of a living thing (our civilization):
A book is a preserving bulwark of civilization against entropy and time, and a platform for further evolutions of thought.
I like that, and would stop there, but again I don’t know how to get to a unique differentia for the book (the definition, for example, could apply to a laptop or television station). And I’m clearly torn between a genus that is tugging in two directions: is the book a preserving bulwark against entropy or a platform for further evolutions in thought? I like both of these ideas so much that I can’t part with either of them. And I’m once again stuck with shifting, for a differentia of the book, to its physical properties. So perhaps this is about as precise a definition of the book that I can arrive at (and notice that, to make the sentence run smoothly, I have placed the differentia first):
Made of paper and ink pages spinal bound, a book is a preserving bulwark of civilization against entropy and time, and a platform for further evolutions of thought.
There’s nothing exactly like it, is there?