deconstruction not rendering things meaningless

Below is a portion of an essay that sort of helped me understand deconstruction a little better. I think.

http://jamesfaulconer.byu.edu/deconstr.htm

Deconstruction
by James E. Faulconer
(Revised 15 June 1998)

To think about the difference between Heidegger's and Derrida's notions of deconstruction, consider an example: I am writing a book on community. I will work over it repeatedly until I am satisfied that I am done. But what does done mean? Doesn't it mean "say everything I want to say"? And what do I want it to say? Everything. Everything, that is, about what it means to be a community. Of course, there will be this or that minor point that I may ignore or safely overlook, but as long as something significant remains to be said about my topic or as long as the connections of important points have not been made clear, I am not done. When I am done, therefore, I have produced something that claims to say everything of importance on my topic; that I have written the book on my topic is implicit in its existence as a book, even if I insert footnotes and apologies and disclaimers to the contrary.
However, when I have finished the book and have (I hope) a publisher, what is the first thing I will do? I'll write an introduction. But introductions are odd things. If they can say what the book says, then what need is there for the book? If they can't, then what need is there for the introduction? Sometimes they are appetizers, things designed to get people to read the book (or at least to buy it). Most of the time, however, an introduction is a short version of the book, an overview. It sets the problem in context, it shows the readers how important the problem or solution is, it gives the argument in a more easily understood form. Introductions add to the book to improve it, to supplement its work.
Thus, though the book implicitly claims to say everything needed, as a supplement, the introduction says "one more thing" or "the same thing briefly," deconstructing the book's claim to completeness and self-sufficiency. In deconstructing the book, the introduction doesn't show us the irrelevance of the book. It doesn't show us that the book is meaningless. It doesn't show us that just any interpretation of the book will do. It shows us that the book claims more than it can deliver, that it has left something out though it claims to be complete. I take that to be the general meaning of the word deconstruction as Derrida has used it: not just using our words and concepts against themselves, but showing what has been left out or overlooked. In fact, better: showing that something has been left out or overlooked, that omission is structural to any text -- and that we can find those omissions in the structure of the text -- without necessarily being able to specify what has been omitted.
Notice, however, that once, by means of a deconstruction, we have seen something that was omitted, we won't be able to go back, insert the missing piece, and then be finally done. The omission is structural to writing and explaining because it is structural to existence and experience. Omission is unavoidable. The reason why is not difficult to see. For one thing, no one can say everything about anything; things are never that simple, not simple things, especially not "first things."

This inability to say everything is not a failure of language, something to be overcome. Neither is it a point of new-age silliness or old-age magic (though it may be an origin of the latter). It is one of the properties of things.(3) If I hold an object up before someone and ask her to tell me what she sees, she can give a list of the thing's properties. If she works at it, she can make that list very long. It may become ever more difficult to add things to the list, but there is really no end to what she could truthfully say about the object. She can, for example, always relate it to another thing in the universe or even to the list she is making. Though we seldom have any reason to go on and on in such a way, there is, in principle, no end to the length of the description one can give of an ordinary object. As a result, it is impossible to say everything about an object, material or otherwise.