energy and mass
"The relation between energy and mass is like the relation between a
building's height and its shadow's length. The shadow is a projection
of the building, and the mass is a projection of the energy."
Further description in the linked discussion.
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.