Originality is the fine art of remembering what you hear but forgetting where you heard it. ~Dr. Laurence J. Peter
It is a gift for a writer to be able to create a one sentence quote which "is worth a thousand words."(1) Occasionally, we will find these on Twitter, limited to 140 characters. More often, they are lifted out of blog posts, books, speeches or published articles.
Dr. Peter's quote is tongue in cheek and typical of human behaviour. With Google, it only takes one or two searches using key words to discover who truly was the first to speak a quote. To not give them proper credit is, at best, lazy. Since it's a violation of copyright, the terms "thief" and "pretender" come to mind. Perhaps, though, it is simply ignorance or lack of respect, both of which could be overcome. Give credit where credit is due or it discredits you. It might even save you a lawsuit.