limitation and opportunity.

....'metaphor started growing ragged and incoherent very quickly; it went from positive analogy to negative analogy. If the model was a planetary one, then how come the electrons were not continually losing energy in their orbits, as one would expect? If the inside of an atom were really functioning according to its metaphoric other half then the electron would soon lose its necessary energy and spin counter-clockwise into the nucleus. And in any case, since the force of the nucleus is positive and that of the electron negative, why don’t the two simply get together as soon as possible? Either way, there would be no atom. The metaphor only works if (however remotely) this can still be said to be that.'