ebb and flow

ebb and flow idiom
A decline and increase, constant fluctuations. For example, He was fascinated by the ebb and flow of the Church's influence over the centuries. This expression alludes to the inward and outward movement of ocean tides. [Late 1500s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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