Artistic Validation - Separate From Selling My Work

Artistic Validation
The artist is nothing without the gift,
but the gift is nothing without the work.
Emile Zola
1 - Introduction
How do you achieve artistic validation?  How do you know if your work is legitimate and recognized as art?
These questions came to the forefront during a recent one on one session when I asked one of my students what were his long-term photography goals.  His answer was that he wanted to sell his work.  Because this student is financially well off I asked him why selling his work was an important goal for him.  His answer was that having people buy your work is proof of artistic validation.
This surprised me because no matter how far back I go I have always considered selling my work to be proof of financial success (or failure as the case might be).  In short, I sell my work to make money.  I run a fine art photography business and selling my work is one of the ways I generate income.
2 - Sales and artistic validation
This is not to say that artistic recogn...