How do people draw from memory?

How do people draw from memory? 

I’m thinking about Olivia right now—after a couple of days with her, her face is more clear to me than my own by many orders. When I picture her in motion, she is three dimensional; so real that it flirts with hallucination. But I can’t look at her in detail. I couldn’t draw her, could I? She won't hold still. When I reduce her to lines, when I take a freeze-frame of her face straight on and try to subtract, one-by-one all of the life, depth and color that makes her the living O., when I try to make her a kind of constellation of places I could drop my pen, the result looks ridiculous and like no one.

How do they do it? Is there a process? Is there a trick? Is all of art like this and everything I write that I remember just some soulless sketch resembling nothing?

This is very distressing.