I went on a crash GKC diet in my twenties. In addition to a score of Chesterton books, I read three biographies about the great man, plus his Autobiography.
But I realized earlier this month that I had never read the first biography, which was written by his friend, Maisie Ward, and is reputed to be a biographical classic. She published the big volume in 1944, just eight years after GKC died.
Most people in the modern world have a left-hemispheric brain that bullies the right (the emissary taking over the master).
Chesterton's brain, by contrast, had a big, powerful, jovial right-hemispheric master that smothered the left hemisphere and often kept it from performing its proper functions. "Aw, don't go slay that orc yet! Stay here and drink another pint."
His genius and overweening right hemisphere showed him how deranged the modern world had become. He could see that the rogue left hemisphere was causing great damage. He even saw that modernity resembled mental maladies on a grand scale, which is the subject of Chapter 9 of McGilchrist's The Matter with Things ("What Schizophrenia & Autism Can Tell Us") and was (kinda, in his roving ambulatory way) the subject of one of GKC's most famous chapters, "The Maniac," in Orthodoxy.
If you decide to tackle him, be forewarned: he weighed over 300 pounds and so did his prose. But it's worth the effort. Many decades later, I often look at my thought processes and see I'm merely trodding in the furrows left behind by his books.