A Shrine To Poseidon

"When Theonis endowed remodeling of the shrine and rededication to Poseidon, with a regular priest coming out of the city from time to time to conduct rites, no one objected. They simply identified this deity with theirs, continued using the old name if they wished..."
-Poul Anderson, The Shield Of Time (New York, 1991), p. 102.

Parochial practices; profound processes. People explain phenomena by personifying and/or unifying them. Mere personification generated a multiplicity of gods. Then unification reduced the number of gods as some were identified with others. When the number has been reduced from many to one to none, and thus personification ceases, explanations remain unitary.

Unification is religious, philosophical and scientific. Religious unification is monotheist (there is one divine being) or monist (the one being is not ontologically distinct). Philosophically, one reality underlies many appearances. Scientifically, one general law explains many particular events, more general laws explain less general laws and scientists seek a unified field theory and Theory Of Everything. They no longer personify. Meteorologists and oceanographers do not refer to Poseidon when explaining a storm at sea. If they did, then we would need a practical polytheism.

Some of SM Stirling's characters begin unifying while still personifying. Tarmendtal thinks that the sun and sea gods are universal. He wonders whether the Lady is the same in another continent and just has many names. (On The Oceans Of Eternity, p. 251)