Who is a true Master? and What is the highest level of attainment one can acquire in any craft?

"Every child is an artist. The problem is how to remain an artist once he grows up."  by Pablo Picasso.

In our professional journey we all want to become masters of our field. We want to attain highest skill set possible.  And to be honest being an Amateur feel Demoralizing sometimes. So this episode is an attempt to go deeper in the question, that "What is the highest level of attainment one can acquire in any craft?"