The entire post can be found at Renegade Parent.
Here's a quote from this wonderful post:
"When I listen to my child's speech developing daily, or when I watch my partner programming in a new language he has learnt, or when I read about new ideas and work them through to a satisfactory conclusion in debate, then I understand the nature of real learning - tested time and again not by a teacher but against the rigorous standards of reality. Can my child make herself understood? Will customers buy the software? Does my logic stand up to public scrutiny?"