The uncertainty principle revolutionized scientific thinking by calling into question the determinism that had prevailed hitherto. The author takes up a few paradoxical notions from quantum physics, such as the theory of entanglement and delayed choice, and then attempts to show that psychoanalysis also accords an important place to indeterminacy and paradoxes, illustrating this with a clinical vignette. The squiggle game devised by Winnicott, which promotes the overlapping of the patient’s and therapist’s areas of illusion, is used in the therapy of a depressed adolescent who has difficulties with symbolization. This technique contains the paradox of an unpredictable and as yet unthought dimension, but one that may be actualized in the session. The author looks at the relevance of drawing analogies between quantum physics and psychoanalytical concepts such as après-coup, the transitional area and the found-created object, and even at the deeper links between these two fields.