My grandfather constructed crossword puzzles for several magazines and newspapers, from 1955 until his death this year, 90 years old. He was extremely knowledg

My grandfather constructed crossword puzzles for several magazines and newspapers, from 1955 until his death this year, 90 years old. He was extremely knowledgeable, and kept a lucid mind until the very end. I don't doubt that his work was the main reason for this.