Could not have said it better

“No one scheme of classification, more than any other, represents the real structure or order of nature. Nature indifferently submits to any and all divisions which we wish to make among existing things. Some classifications may [seem to] be more significant than others, but only by reference to our interests, not because they represent reality more accurately or adequately”.

This quote is from "Object Oriented Analysis and Design". I like the book a lot (although, it could have been shorter), and it's the best part there. If you stop to think about what it says, you will probably find that it's very true. Not only does this apply to object-oriented classification, but for any other classification or schema out there. I could talk for hours about this, but since I promised to keep everything short, I will just say: the life itself is incomprehensible.