The recognition of aquifer storage and its physical basis was key to solving two problems in the understanding of the origin and movement of groundwater. Meinzer (1928) demonstrated that aquifer compressibility and loss of pore volume from pore pressure decline accounted for about 80% of the water consumed by irrigation in South Dakota over a 40‑year period around the turn of the 20th century. Theis (1935) invoked the property of storage by analogy with heat transport to solve the problem of time‑dependent change in head due to pumping a well. Jacob (1940) derived the groundwater flow equation from scratch by explicitly considering the physical basis for storage in terms of aquifer compressibility and water compressibility. This narrative in three acts transitioned the understanding of groundwater flow from steady state to “non‑equilibrium,” transient behavior.