evidence: Charles Dodgson (1832-1898), whose pen name was Lewis Carroll, was an English author, mathematician, logician, photographer, and church deacon best known for writing the books Alice's Adventures in Wonderland and Through the Looking-Glass. He wrote a book of 72 mathematics problems, titled Pillow Problems thought out during Wakeful Hours, which he said he had personally worked out without putting pen to paper, and here is problem 5: