Rule of Phase Applied to History

The "Rule of Phase Applied to History" is an essay by American historian Henry Adams. Adams, a descendant of presidents John Adams and John Quincy Adams, was a prominent historian and author.1

In his essay, Adams applied a scientific law, the "phase rule" from physical chemistry, to historical analysis. The phase rule, in chemistry, relates the number of phases, components, and degrees of freedom in a system at equilibrium. Adams theorized that civilization progresses through distinct stages, which he identified as religious, mechanical, electrical, and ethereal. He predicted a cataclysmic end to civilization, which he prophesied would occur in 1921. The extent to which Adams intended this prediction literally remains a subject of scholarly debate.21