In the first version we learn and discover, edits and rewrites.<p>In the second version we build with symmetry and regularity.<p>We need both versions, and in the second we drop some corner cases to make things crystalline. It is important to recognize the things we drop and why, sometimes they are important, but the purity of the construction takes precedent. And sometimes the corner cases are the thing, without them the chandelier would cast no light.<p>Anyway, I don&#x27;t know where I am going with this. Small, playful, understandable systems are the most informative.  We need playful, useful models that can be used for experimentation in a momentum free way. And it is important not to suffocate the future with exhaustive engineering. Recognize the is.