A crescendo is a gradual increase to the highest or loudest point, while diminuendo is the complete opposite. So the composer wants to contrast these two very different textures.
BONUS: A slow movement's has a contrast that is usually fast that is placed in the middle or end.
Answer: According to Hockney photography has it limits as it cannot capture time. He explains as it only has a singular point of view, and that photography is only good for mechanical reproduction.
