I have found Gall's law to be a corollary of "mastery before tools": "A complex system that works is invariably found to have evolved from a simple system that

I have found Gall's law to be a corollary of "mastery before tools": "A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works and cannot be patched up to make it work. You have to start over, beginning with a working simple system."