I completely agree with PG.

Writing is not just communication with others, or writing down information for later.

Writing is not just writing down something that already exists in the mind.

Writing is a part of thinking process. You talk to yourself few seconds or minutes later. It's back-and-forth. Marshaling thoughts and ideas, reading them back, reflecting, to be processed then writing them down again.

Writing is process of improving thoughts, generating new thoughts and ideas, making thoughts clearer for yourself.