C.S. Lewis, the famous author of the Narnia series, but also a philosopher and theologian said:

“I do not sit down at my desk to put into verse something that is already clear in my mind. If it were clear in my mind, I should have no incentive or need to write about it. We do not write in order to be understood; we write in order to understand.”

This relationship between thinking and writing is what excites me about the writing process. Expressing our thoughts in words forces the abstract and the fuzzy to become concrete and definite.

It does allow us to share our thinking with other people. But perhaps even more usefully, writing our thoughts down allows us to share our thinking with ourselves, helping to refine our thoughts and develop richer and more useful ideas.