In this case, the author's exact words are essential if you want to get across exactly what Romeo is feeling. In science, the author's words almost never matter . A to a test tube, and then shake vigorously for 2 minutes. In your lab report you do NOT want to quote this. This conveys the necessary information but doesn't steal someone else' words to do it.
Many students try to get away with copying from a source, but making one or two minor changes.
It's the east, and Juliet is the sun. Don't think you can copy from your lab manual, your text book, or any other source, and just make some minor changes.