"First of all, a paraphrase is generally much shorter than the original. But there are cases in which the author of a sentence or fairly short paragraph says very juicy things. In this case, your paraphrase should be very long, probably longer than the original passage. . . . The most reassuring test of your paraphrases will come when you are able to paraphrase the text without looking at it. This will mean not only that you have avoided plagiarism, but also that you have understood the text you are paraphrasing" (165).
Eco, Umberto. How to Write a Thesis. MIT P, 2015