Some people are under the impression that paraphrasing avoids plagiarism.  This is not really true.  To help me explain, I will give you Google's definition of plagiarism: "Based on this definition [while will be correct by almost anyone's definition of plagiarism] paraphrasing cannot be used to avoid plagiarism.  That is, paraphrasing simply makes plagiarism harder to detect. By paraphrasing someone else's work, I am still plagiarizing it.

For example (from Wikipedia, on "A Brief History of Time . . . ." by Stephen Hawking (in green text as a direct quote to avoid plagiarism):

• "The first edition [of this book] included an introduction by Carl Sagan that tells the following story: Sagan was in London for a scientific conference in 1974, and between sessions he wandered into a different room, where a larger meeting was taking place. "I realized that I was watching an ancient ceremony: the investiture of new fellows into the Royal Society, one of the most ancient scholarly organizations on the planet. In the front row, a young man in a wheelchair was, very slowly, signing his name in a book that bore on its earliest pages the signature of Isaac Newton... Stephen Hawking was a legend even then." In his introduction, Sagan goes on to add that Hawking is the "worthy successor" to Newton and Paul Dirac, both former Lucasian Professors of Mathematics.[5]

The introduction was removed after the first edition, as it was copyrighted by Sagan, rather than by Hawking or the publisher, and the publisher did not have the right to reprint it in perpetuity. Hawking wrote his own introduction for later editions."

My point (see especially the red text)?  No matter how many ways Hawking might have paraphrase the quotation by Sagan, it would still be plagiarism because it was Sagan's idea, not Hawking.