Winnicott, D. W. (1953). Transitional objects and transitional phenomena; a study of the first not-me possession. The International Journal of Psychoanalysis, 34, 89–97.
The first possession of an infant is related backwards in time to autoerotic phenomena like thumb-sucking and forward to the first toy recognized as such. It is related to, and midway between, the external object (mother's breast) and internal objects (magically introjected breast). This intermediate area of transitional objects and transitional phenomena is made possible by the mother's adapting herself to the needs of the infant, thus allowing the infant the illusion that what it creates really exists. This area of experience constitutes the greater part of the infant's experience and is retained throughout life in the form of religious, creative, imaginative, and speculative living. (PsycINFO Database Record (c) 2018 APA, all rights reserved)
