Ah ha! *The register transfer level - I was looking for you.
   Analogies: registers remember. combinational logic has no
   memory. "A synchronous circuit consists of two kinds of
   elements: registers and combinational logic. Registers (usually
   implemented as D flip-flops) synchronize the circuit's operation
   to the edges of the clock signal, and are the only elements in
   the circuit that have memory properties." And after researching
   flip-flop, I came across this marvelous article. which contains
   an interesting fact about how some [1]#humans *devotion to
   [2]#purelogic*flies in the face of [3]#reality *: "Serious
   computer and digital hardware bugs caused by metastability have
   a fascinating social history. Many engineers have refused to
   believe that a bistable device can enter into a state that is
   neither true nor false and has a positive probability that it
   will remain indefinite for any given period of time, "
   [4]https://en.wikipedia.org/wiki/Metastability_in_electronics

References

   Visible links
   1. https://plus.google.com/s/%23humans
   2. https://plus.google.com/s/%23purelogic
   3. https://plus.google.com/s/%23reality
   4. https://en.wikipedia.org/wiki/Metastability_in_electronics