Kilroy J. Oldster said this quote
“ Talking to oneself is a recognized means to learn, in fact, self-speak may be the seed concept behind human consciousness. Private conversation that we hold with ourselves might represent the preeminent means to provoke the speaker into thinking (a form of cognitive auto-stimulation), modify behavior, and perhaps even amend the functional architecture of the plastic human brain. Writing out our private talks with oneself enables a person to “see” what they think, a process that invites reflection, ongoing thoughtful discourse with the self, and refinement of our thinking patterns and beliefs. Internal sotto voice conversations with our private-self provide several advantages, but most people find it difficult to maintain self-speak for an extended period. Internal dialogue must compete with external distractions. Writing allows a person to resume a personal dialogue where they left off before interrupted by outside stimuli. A written disquisition also provides a permanent record that a person can examine, amend, supplement, update, or reject. ”