ebb and flow

:  the reflux of the tide toward the sea

:  a point or condition of decline

:  to recede from the flood

:  to fall from a higher to a lower level or from a better to a worse state

:  to issue or move in a stream

:  circulate

:  to move with a continual change of place among the constituent particles

:  an act of flowing

:  flood

:  flood