In a way, playing remains an important educational factor for the whole life. Of course, I do not mean the card game here, because all games that are directed to the intellect claim the personal of the human being that is bound mostly to the instrument of the brain. Even if much favourable is said about chess, it can never be a factor of self-education because it depends on that which is bound mostly to the instrument of the brain that has to infer. If the human being is active with gymnastics where he has to set his muscles in motion in such a way that he can infer nothing at all that he does not strain his intellect, but directly develops with the activities and not with intellectual understanding, then we deal with a self-pedagogic play.
From it, we directly gain an important principle of any self-education. This is that the human being who has to educate himself by the education of his intellect and in particular by the education of his will depends on the care of the contact and interrelation with the outside world. The human will can be educated not by inner intellectual training, but it strengthened, so that the human being has a firm hold inside if he maintains the will while the own will and the outside world interact.
Source: Rudolf Steiner – GA 61 – Human History: Lecture XIV: The Self-Education of the Human Being – Berlin, March 14, 1912