"If circuits are like plumbing, then none of the "pipes" of a circuit are ever empty. This idea is extremely important, and without it we cannot understand semiconductors ...or even conductors! Metals contain a vast quantity of movable electrons which forms a sort of "electric fluid" within the metal. A simple hunk of copper is like a water tank! Physicists call this fluid by the name "electron sea of metals," or "the ocean of charge." Semiconductors are always full of this movable "charge-stuff." The movable charge is in there even when a transistor is sitting on the shelf and disconnected from everything"
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.