Early on, Doug Engelbart recognized that what makes us capable, beyond the basic human abilities we were born, is a whole infrastructure of capabilities, with higher level capabilities depending on the execution of lower level capabilities. For example, the ability to solve a problem collaboratively depends on our ability to communicate with language, to use acceptable conventions and methodologies for working together, to identify opportunities, plan, implement, write, discuss, etc.
Human system and tool system are the foundations of capability infrastructure.