"Writing, after all, is nothing but speaking on paper, speaking is nothing but thinking out loud, and thinking is nothing but silent speech."
I disagree with Rudolf Flesch. From personal observations I would say that inner thoughts, even verbal inner thoughts, are in general less structured than spoken language or the written word. Since we think for ourselves and not primarily for communication with other individuals, our thoughts are less constrained in form and have higher degrees of freedom. The spoken or written language should be understandable for other persons. For that reason the spoken and written word has to be highly structured and constrained in form. On average, thoughts are less structured than spoken words, and spoken words are less structured than written words.