Romanticism has very little to do with things popularly thought of as "romantic," although love may occasionally be the subject of Romantic art. The core philosophy behind Romanticism was the idealization of reality.
In the late 18th century, it came to mean anti-Classical and represented a trend towards the picturesque and the Gothic, and a love of nostalgia, mystery and drama, Because of this sweeping nature of Romanticism, most critics will tell u that Romanticism was little more than a “feeling”.
However it cannot be dismissed so easily because it was influenced by ideas of the Enlightenment, particularly evolution and uniformitarianism, which argued that "the past is the key to the present", and elevated medievalism and elements of art and narrative perceived to be from the medieval period. The name "romantic" itself comes from the term "romance" which is a prose or poetic heroic narrative originating in the medieval.
During this period Landscape painting was seriously explored by Constable, Palmer and others. The Middle Ages were seen as a source of artistic and architectural interest. Most significantly Turner employed a very distinctive technique of expression which gave us an understanding of the popular view of the natural world. In France the movement was politically motivated by the revolutions of 1789 and 1830, and with the patronage of Napoleon. Artists looked increasingly to literature, history and exotic subjects. The art pour art movement promoted beauty for its own sake. Painters like Delacroix experimented with new color theories and free brushwork.
Romantic Painters and Nature
Nature meant more than flora and fauna to the Romantics. As stated above, it was often presented as itself a work of art, constructed by a divine imagination, in emblematic language. A blade of grass was not just a blade of grass; the tiny frame of the grass encompassed the entire human experience- of love and suffering, of the cycle of life. At the same time, Romantics gave greater attention both to describing natural phenomena accurately and to capturing "sensuous nuance"-and this is as true of Romantic landscape painting as of Romantic nature poetry. Accuracy of observation, however, was not sought for its own sake. Romantic paintings were after all paintings of meditation.
Imagination –the core Romantic Quality
The imagination was seen as the supreme faculty of the mind. This contrasted distinctly with the traditional arguments for the supremacy of reason. The Romantics believed and defined imagination as our ultimate "shaping" or creative power. The ability to imagine made man what he is and therefore he has to use it to make the world a better place.
Romanticism can be seen as an unnecessarily idealistic philosophy but it would be more judicious to view it is an international artistic and philosophical movement that redefined the fundamental ways in which people in Western cultures thought about themselves and about their world.