Basically, the teachings of Russell were an amalgam of Brown's and William Miller's teachings, with a dose of his own ideas as well as pyramid dimensions. In fact, he paid Nelson Barbour, a Millerite, to write "Three Worlds and the Harvest of This World" in 1877. They later went seperate ways, and Russell started printing his own material in 1879.
The examination of early Adventism is always interesting, and shows that this religion has always borrowed heavily from other religious viewpoints. Yes there is nothing new under the sun!
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