By the mid-nineteenth century, artists turned their attention to the unique geological features of Yosemite. These western landmarks became symbols of American expansion and prosperity. William Keith painted this majestic scene soon after meeting John Muir, the environmentalist and founder of the Sierra Club. Muir’s ideals of truth, character, and grandeur of nature became Keith’s artistic aims. To convey the sheer size of Sentinel Rock, Keith added figures to the foreground, tiny in comparison to the massive rock jutting up into the sky.