the facilitating environment makes possible the steady progress of the maturational processes. But the environment does not make the child. At best it enables the child to realize potential. This term ‘maturational process’ refers to the evolution of the ego and of the self
Winnicott’s canonical definition distinguishes maturational processes as an innate developmental programme — covering ego, self, id, instincts, and defences — that the environment can facilitate or obstruct but never author.
, The Maturational Processes and the Facilitating Environment, 1965thesis