The term “transitional” was introduced by Winnicott (1953) to describe that intermediate phase of development in which the child does not perceive himself as being completely distinct from the object, although he no longer feels it is part of his own body. The beginning of this phase is indicated by certain actions (transitional phenomena) which accompany the child's thumb-sucking (fiddling with parts of his sheet or blanket, making variuos sounds and noises, etc.). The term “transitional” refers to this very idea of something between the subjective and the objective which marks the gradual shift from the suckling's “illusion” that he himself creates the breast and his consequent disappointment. Winnicott has also described how between the fourth and eighteenth month of the child's life, a single object (for example a blanket) can become of vital importance, above all when the child falls to sleep, and he has called this the “transitional object”. This is the first “not-me possession”.