Ronaldinho has revealed in The Players' Tribune that the proudest moment of his career was "helping to change football in Barcelona" through his style of play.
The former Brazil international won the World Cup, the Champions League, La Liga, Serie A and the Ballon d'Or in a career spanning three decades.
But he said he looked back most fondly on the impact he made at Barcelona after joining from Paris Saint-Germain in 2003.
In a letter to his eight-year-old self, he wrote: "What you'll be most proud of is helping to change football in Barcelona through your style of play.
"When you arrive, Real Madrid will be the power of Spanish football. By the time you leave, kids will be dreaming of playing 'The Barcelona Way.'
"Your role in this will be about much more than what you do on the pitch."
Ronaldinho left when Pep Guardiola was appointed as manager in 2008, having played a huge role in helping the club rediscover an identity lost in the post-Johan Cruyff years.
Guardiola continued that revival aided by Lionel Messi, who Ronaldinho was able to help develop from a highly-rated youth teamer into first team star.
"You'll hear about this kid on the youth team," he adds in his letter. "He wears No.10 like you. He's small like you. He plays with the ball like you.
"You and your teammates will go watch him play for Barcelona's youth squad, and at that moment you'll know he's going to be more than a great footballer. The kid is different. His name is Leo Messi.
"You'll tell the coaches to bring him up to play with you on the senior side. When he arrives, the Barcelona players will be talking about him like the Brazilian players were talking about you.
"I want you to give him one piece of advice. Tell him: 'Play with happiness. Play free. Just play with the ball.' Even when you are gone, the free style will live on in Barcelona through Messi."
In the letter, he also recalled the excitement he felt when playing for Brazil for the first time.
"Playing for Brazil will change your life," he said. "All of a sudden, doors you never even knew were available to you will start to open."