Found at http://citeseerx.ist.psu.edu‌​

When Bohr bemoaned to Ernest Rutherford,‌ “Dirac never says anything,” Rutherford replied with a story about a shop owner assuaging a dissatisfied customer who had purchased a parrot that would not speak. “Please forgive me. You wanted a parrot that talks, and I gave you the parrot that thinks.”