Birth of A Composition

Today I had a conversation with a friend about how I start a composition - do I see the picture fully realized before I begin, or does it start with a simple idea and it just grows as I work?

The answer is yes....
Having one way only vision into a completed work of art doesn't allow for happy accidents, evolution or redirection, that could all make the composition work more effectively, or create a deeper sense of emotional tone.
A fully realized vision in my mind means a direct translation to the page - sometimes there are variations in hues, shading and dynamics, but for the most part, it's a straight path from my imagination through the pencil.

A composition that grows as I work is usually based more on an emotional statement or narrative moment, rather than a visualization - in this case, every kind of change and transformation to the image is available, and there is a journey through the imagination AS I put pencil to page.
Neither method is more effective than the other, and there are degrees in the balance between both methods - I don't restrict myself to one method entirely, I simply pay attention to the result as it emerges in front of me.
If I knew everytime what would be the finished product, there would be no journey to take.