Headshots Paris Portrait by Leonardo da Vinci

What can we learn from this image as an art form for Headshots photography? What are the similarities to modern Headshots for Casting, modern portraits?

One main subject matter vs a non distracting background to add value of the portrait. That is common in modern portraits.

The eyes see you at every which direction, most captivating portraiture photography does the same thing?

Lets hear your comments,

Thanks Artofheadshots.com, Vancouver.