More books that Chesterton wanted to write but never did. 

17. If I ever were to attempt to write a history of the world—which God forbid—and particularly if I were to endeavor to write in that “spirit of impartiality” which seems to mean having no apparent conviction on any subject, the first thing I should say would be: “Human civilization is older than human records.” (St. Louis Post-Dispatch, Mar. 21, 1921)

18. I have often had a vision of a fine cosmic fantasy about finding some wild utility for clouds or comets, and felt inclined to send it on a postcard to Mr. H. G. Wells. (Illustrated London News, Mar. 25 1922)

19. Someday I will write a learned and exhaustive History of England Since the Reign of Richard the Second. (New Witness, Aug. 4, 1922)

20. Some day perhaps I will try to write another and better romance in the manner of the Flying Inn called the Flying Grocer, in which angelic wings shall be given to him in his turn. (New Witness, Feb. 2, 1923) 

21. If ever I write a romance about a Utopia or ideal society (which God forbid) . . . I shall describe the household as conducting domestic life with the rush and romance of an obstacle race. (Columbia, October, 1924)

22. I once very nearly wrote a fairy-tale on the old theme of a country where all wishes come true; and where, as a matter of fact, everybody maintained a terrified silence, being afraid to mention anything for fear it should happen. Not only their fancies, but their figures of speech would instantly materialise; so that, if a man inadvertently observed “I must have lost my head,” his head instantly rolled away like a cannon-ball; or if he said, “I’m rather up a tree just now,” he was borne aloft by a sprouting palm or pine that sprang up immediately under him. The result was that everybody felt a little nervous; as I sometimes think most of us would feel in most of the Utopias and ideal social states. (Illustrated London News, Sept. 12, 1925) 

23. I turn to another story that I never wrote. Like every book I never wrote, it is by far the best book that I have ever written. It is only too probable that I shall never write it…I conceived it as a romance of those vast valleys with sloping sides, like those along which the ancient White Horses of Wessex are scrawled along the flanks of the hills. It concerned some boy whose farm or cottage stood on such a slope, and who went on his travels to find something, such as the effigy and grave of some giant; and when he was far enough from home he looked back and saw that his own farm and kitchen-garden, shining flat on the hill-side like the colours and quarterings of a shield, were but parts of some such gigantic figure, on which he had always lived, but which was too large and too close to be seen. (“Introduction,” The Everlasting Man) 

24. I think I shall try some day to write a huge philosophical and critical work called “The Point: Its Position, Importance, Interest and Place in our Life and Letters.” It would have separate sections On Seeing the Point; On Missing the Point; On Getting to the Point; On Wandering from the Point, and so on. The subject would be so vast and various that I think it would have to be arranged in the form of a sort of Encyclopaedia. Thus we should have: Point, the, obvious to born fool; see Fool. Point, is it rude to? Points, kindred, of heaven and home; see Ornithology. Point of pin, use of, when justified; and so on. Point evaded by Professor Robinson, and all the rest. But, anyhow, the subject of this great work is very real, much more real than the work itself. It concerns the whole of that great search for reality which is the main adventure of the mind. (Illustrated London News, Oct. 30, 1926) 

25. I should like to write a book under the general title of The Timid Thinkers. By this term I refer to those who are commonly called The Bold Thinkers. (Illustrated London News, Nov. 9, 1929)

26. Sometime or other, I think, I will write a really thoughtful and educational article about Bed or Breakfast or Baths or Breathing, or some of those simple things, or things that seem simple to simple people. And it shall be written in the exact and peculiar style of a modern article on Marriage or the Family or Patriotism or Religion. (Illustrated London News, April 4, 1931)

27. I do sometimes waste a great deal of time thinking about the stories I could not write. I mean that I sometimes think a great deal about the themes or crises of stories that somebody else could write much better than I. It seems as if there ought to be some sort of imaginative exchange and mart, or literary clearinghouse, by which each one of us could get rid of a plot or plan which we could not ourselves carry out, but which somebody else might be exactly suited to carry out. (Illustrated London News, June 24, 1933)

28. In my youth – I might almost say in my boyhood – I planned a magnificent prose epic about a war between Pessimists and Optimists for the destruction or deliverance of the world. (Illustrated London News, June 24, 1933)

29. No. 999 in the vast library-catalogue of the books I have never written (all of them so much more brilliant and convincing than the books that I have written) is the story of a successful city man who seemed to have a dark secret in his life; and who was eventually discovered by the detectives still playing with dolls or tin soldiers or some undignified antic of infancy. I may say with all modesty that I am that man, in everything except his solidity of repute and his successful commercial career. (“The Man with the Golden Key,” Autobiography)