Let them be little

Play is the highest form of research
— Albert Einstein
You can discover more about a person in an hour of play than in a year of conversation.
— Plato
Men do no quit playing because they grow old; they grow old because they quit playing.
— Oliver Wendell Homes Jr.
It is a happy talent to know how to play.
— Ralph Waldo Emerson
A child loves his play, not because it’s easy, but because it’s hard.
— Benjamin Spock

Never stop playing, sweet boy. You are a wonder to watch and it is one of my chief joys to play with you.