In Arnold Böcklin's Sanctuary of Hercules, three soldiers kneel reverently on the outer step of a shrine, while a fourth looks defiantly off into the distance. The sky, a rich panoply of gray, blue, and white, signals an approaching storm, and a strong wind whips through the trees, scattering the leaves and ruffling the plumes on the soldiers' helmets. At the painting's focal point is the sanctuary itself constructed of stones which are trimmed with polished marble and rest upon an equally smooth circular base. Within the enclosure is a sacred grove of massive trees and at the back, seen in darkened profile, a statue of Hercules, mythical hero and protector from danger.
At first glance, the subject appears very realistic and the shrine archaeologically accurate. Yet the scene also conveys a definite mood of mystery. The stones' pure and richly harmonious colors glow with an unnatural radiance. The gloom inside the grove is equaled by the dark ominous clouds, lit by flashes of lightning on the horizon. Indebted to the romantics of the first half of the nineteenth century, Böcklin rejected the idea of painting solely from nature, and strove to express his own feelings through nature, with the use of vibrant coloration and dramatic lighting.