4 D O C S . 4 , 5 J A N U A R Y 1 9 1 9 4. From Theodor Vetter [Zurich,] 28 January 1919 Dear Sir, Yesterday you made a statement to Mr. Gattiker to the effect that supervision at your lectures was not necessary and through your personal intervention you obliged the university official to leave his post. I take the liberty of informing you that Mr. Gattiker acted strictly on the order of the university president’s office and he must appear in the future, too, for supervi- sion until the situation is under control. Any lecturer of the university or of the Fed. Polytechnic (not teaching assistants) obviously has free access to your lectures whoever else wishes to participate must register according to the official directive and pay the fee. Now the university cashier reports that many students have already demanded their payments back because they cannot find a seat in the auditorium. This must be avoided, for plenty of room is available, but it is taken up by people who are not entitled to attend your lectures.—That is why the control is necessary, which inci- dentally is in your very own interest. Surely, you do not wish to see before you a constantly changing crowd of curious onlookers but, rather, a serious audience who intends to follow your lectures consistently. Allow me, therefore, to make the request that henceforth you kindly refrain from interfering with the instructions of the president’s office. With utmost respect, The University President. 5. To Arnold Sommerfeld [Zurich,] 5 February 1919 Dear Sommerfeld, Your friendly invitation pleased me very much. But this time you must kindly grant forgiveness. I’ve almost had to preach my lungs and brains out here already, so I have a proper craving for rest. Added to that, I actually don’t really have any- thing new to present, just a rehash. So let me go my own quiet way. As a mitigating circumstance I must add that my stay here has been delayed by 3 weeks anyway as a consequence of the “heating vacation,” which lasted until January 20th. With cordial greetings, yours, Einstein.