121. Read the following passage, then answer the question below.

When the first practical photographic processes appeared in the 1840s, many painters feared for their profession. Why would anyone pay for a portrait or a landscape when a camera could record a scene in minutes? The art critic Charles Baudelaire dismissed photography as art's most mortal enemy. Yet the history of nineteenth-century painting suggests that the camera did not destroy painting so much as free it.

Before photography, much of a painter's income came from realistic likenesses: portraits of merchants, records of battles, and views of famous places. Once these tasks could be done faster and more cheaply by machine, painters had both the incentive and the freedom to explore what a camera could not capture. The Impressionists of the 1860s and 1870s, including Claude Monet and Camille Pissarro, painted fleeting effects of light and atmosphere rather than precise detail. Early cameras, which required long exposures and rendered color in shades of gray, were incapable of recording a sunrise over a harbor as the eye perceives it. Monet's Impression, Sunrise, whose title gave the movement its name, was a deliberate statement that subjective experience mattered more than documentation.

The influence also ran in the opposite direction. Painters borrowed from photography's unusual compositions, such as figures cropped at the edge of the frame or viewpoints from above, which broke with the centered, balanced arrangements of academic painting. Edgar Degas, who owned a camera, used such devices in his scenes of dancers. At the same time, photographers like Gustave Le Gray imitated painting by softening focus and printing in warm tones to convince critics that photography could be art.

The relationship therefore resembles a negotiation more than a rivalry. Each medium defined itself partly by its difference from the other, and the boundaries they drew continue to shape how we think about both.

What is the main idea of the passage?