The search for simplicity was known to the ancient Greeks as ‘LOGOS’. However, where and when this is combined with personal ‘EGOS’ the results are subjective theories not strictly based on the scientific method. Later, if the underlying hypotheses turn out to agree with observations and experimentations then the theories become physical laws and would apply to all the sciences and modern technology. For over two thousand years many physical theories have been debunked but many more have became unbreakable principles for more progressive endeavors in the sciences.

On the other hand, the progress of descriptive mathematics begins with simple axioms and theorems from simple counting arithmetic to algebra, geometry, trigonometry, and gradually evolved into complex imaginary of abstract algebraic topology, multi-variable complex analysis, tensor calculus, differential geometry, joint probabilities, and abstract sets and categories. For the former the simplest TOE would be to unify both quantum mechanics and general relativity. For the latter, the most complex would be to organize the cohomology and BRST quantization of superstring theories. http://en.wikipedia.org/wiki/BRST_quantization