Four-ray problem (How many rays cut four given rays?) as offering best apercus into nature of projective geometry. The impossibility of exact ideas, even in mathematics. Idea of a person idea of a species of animal. Reality and entia rationis. Brief note on verso of one of the pages is dated September 16, 1906, and reads as follows: "11 1/4 P.M. Fell asleep standing and dreamed something about a tablet in a church In memory of my mother."
Ens rationis, Fourray problem, graphics, Ideas, Mathematics, Reality
pp. 1-10, with 28 pp. of other drafts