Why Capacitor stores Energy? Why Capacitor Blocks DC?

Capacitor Analogy

In the hydraulic analogy, a capacitor is analogous to a rubber membrane sealed inside a pipe. It is possible to push water towards the membrane, but as the membrane stretches it will push back against the flow more and more. This animation illustrates a membrane being repeatedly stretched and un-stretched by the flow of water, which is analogous to a capacitor being