Prague, 13 May 1911

'I no longer ask whether these quanta really exist. Nor do I try to construe them, as I now know that my brain cannot penetrate in this way'.

Einstein is delighted with his new position and institute in Prague (in January 1911 he had been appointed professor of theoretical physics at the German University in the city, and director of its institute of theoretical physics), although the Czechs themselves seem very alien to him: he criticises their lack of 'natural feeling', their mixture of condescension and servility, and the contrasts of luxury and poverty around him. His compensation for this isolation is in 'the possibility of indulging in scientific rumination more or less undisturbed ... Just now I am trying to derive the law of heat conduction in solid insulators from the quantum hypothesis. I no longer ask whether these quanta really exist. Nor do I try to construe them, as I now know that my brain cannot penetrate in this way. But I am scanning the consequences as carefully as possible, so as to be instructed as to the range of applicability of this conception'. Walther Nernst has carried out some experiments confirming Einstein's quantum theory of specific heats: 'Certainly, the shape of the curve deviates systematically from the one resulting from Planck's law'.

Einstein urges Besso to come and visit him ('We have a room that has nothing else to do than to wait to be visited by one of my dear friends. Besides, Prague is a wonderful city...') or even to think of settling in Prague for good: 'Don't you sometimes wish you could permanently pitch your wigwam here? We would then both be less lonely. And what agreeable working conditions! ... Think how nice it would be if we could study Grassman's Ausdehnungslehre together'.