This is a sentence from another question asked here today:
And from all these things the soft light proceeded, like the glimmering of pearls in the depth of water, like the phosphorescent light that moves of itself on the night surface of southern seas, or shines round the heaving shoals, milky-white over their silver darts, in our own dark Channel.
The lyrical and metaphorical image that this sentence presents seems clear to me. What bothers me is the phrase "moves of itself". Does "of itself" here mean the same thing as and come from "in and of itself"? If so, is this a strange/stilted usage? Doesn't "in and of itself" mean something considered alone and appear mostly in legal/philosophical texts?
It seems the sentence could have been written as "the phosphorescent light that moves on the night surface of southern seas". What does "of itself" do in this sentence?