When something happens that is completely opposite the audience expects.
The main idea is found by looking at the general idea of the text you are reading, what is it about? What does it mention?
Poe creates contrast in his portrayal of the bird in "The Raven" by placing the black bird on the marble statue. The contrast between the darkness of the bird and the whiteness of the statue is quite striking, exactly the thing he wanted to achieve.
Explanation:
उज्ज्ज्ज्ज्ज्ज्जिउउउय्त्फ्फ्ह,त्घ्हु