India, Sept. 4 -- We knew it was coming, but Lionel Messi's retirement from international football still feels momentous.

The 39-year-old Argentine great made his decision public on social media this week, posting an image that evoked a different era: three lined pages, torn from a notebook, carrying an emotional note written in his neat, childlike hand.

In 2005, when he made his international debut as a floppy-haired 18-year-old, pen and paper were what he would have still used at school, or in the La Masia academy classrooms. (The first iPhone was still two years away.)

In that debut match, against Hungary, the teen lasted less than two minutes before being sent off for a foul that, today, would likely have seen the red card overturn...