The son could only talk to his father in the sister's absence? Despite the ostensible 'answer' given at the end that God exists in the form of love, the film is full of ambiguities, as all the characters' reliability remain in question till the end.
But what if I am blind? What if I am so numb that could feeling nothing even pain? What if I am poor to death, to stink, to disability of movement? What if I know nothing about Shakespeare?