The solution of the difficulty is that the two mental pictures which experiment lead us to form - the one of the particles, the other of the waves - are both incomplete and have only the validity of analogies which are accurate only in limiting cases.
Werner HeisenbergEven for the physicist the description in plain language will be a criterion of the degree of understanding that has been reached.
Werner HeisenbergA consistent pursuit of classical physics forces a transformation in the very heart of that physics.
Werner HeisenbergNature allows only experimental situations to occur which can be described within the framework of the formalism of quantum mechanics
Werner Heisenberg