Naturalism attempts to portray visible reality with absolute accuracy. It does not select between important and unimportant elements of reality: each detail is considered to be equally important. For naturalist painters from the 19th century onwards, any detail, however simple, was suitable for portrayal. They give up clichés of iconography and compositions which were obligatory for ideal landscapes. In order to accurately portray the optical vision of nature, artists analysed what they saw, contributing to the development of plein-air and impressionism, too.