The scope of thoughts you can write is much broader than the scope of thoughts you can think on your own. Written language, much like computer code, can express programs that are out of reach for brains alone. Write to think. twitter 
François Chollet:
Deep learning at google. Creator of Keras, neural networks library. Author of "Deep Learning with Python". twitter
In particular live thoughts have limited recursion depth, and only have access to limited working memory; written thoughts have unlimited recursion depth, and paper has unlimited memory.
The key steps in our cognitive development so far have been language, writing (and its corollary the printing press), and computing (and its corollary the Internet). The first two are 100,000 and 5000 years old respectively. Last one is happening right now. We live in remarkable times.
But, The human mind is a vulnerable system that will come increasingly under attack from ever-smarter automation that will simultaneously have a complete view of everything we do and believe, and complete control of the information we consume. medium
Information management algorithms should not be a mysterious force inflicted on us to serve ends that run opposite to our own interests; instead, they should be a tool in our hand.
Can you imagine looking at your own life through the lens of a system that has seen millions of lives unfold? Or writing a book together with a system that has read every book? Or conducting research in collaboration with a system that sees the full scope of current human knowledge?
See Speed Read through hypertext.