"Every perception is to some degree an act of creation, and every act of memory is to some degree an act of imagination."
-- Gerald Edelman, Second Nature: Brain Science and Human Knowledge
4 Tools for thought must be developed while doing serious work. The aspiration to canonical content6 Tools for thought must be developed while doing serious work. The aspiration to canonical contentTools for thought must be developed while doing serious work. The aspiration to canonical contentHow can we develop transformative tools for thought？2020-10-18Journal
Concretely: suppose you want to build tools for subject X (say X = differential geometry). Unless you are deeply involved in practicing that subject, it's going to be extremely difficult to build good tools. It'll be much like trying to build new tools for carpentry without actually doing any carpentry yourself. This is perhaps part of why tools like Mathematica work quite well – the principal designer, Stephen Wolfram, has genuine research interests in mathematics and physics. Of course, not all parts of Mathematica work equally well; some parts feel like toys, and it seems likely those are the ones not being used seriously internal to the company.