Final answer:
The line provided is from Shakespeare's 'Romeo and Juliet,' signifying the striking beauty of Juliet as perceived by Romeo, symbolizing love at first sight.
Step-by-step explanation:
The quote "So shows a snowy dove trooping with crows, As yonder lady o'er her fellow shows" is from Shakespeare's Romeo and Juliet. This line is part of Act 1, Scene 5, where Romeo first lays eyes on Juliet and is struck by her beauty, which stands out among the other women as a dove would stand out amongst crows. This vivid comparison through the use of a simile highlights Juliet's exceptional beauty and purity in the eyes of Romeo, enhancing the theme of love at first sight that permeates this famous play.