Only by strict specialization can the scientific worker become fully conscious, for once and perhaps never again in his lifetime, that he has achieved something that will endure. A really definitive and good accomplishment is today always a specialized accomplishment. And whoever lacks the capacity to put on blinders, so to speak, and to come up to the idea that the fate of his soul depends upon whether or not he makes the correct conjecture at this passage of this manuscript may as well stay away from science. He will never have what one may call the "personal experience" of science. Without this strange intoxication, ridiculed by every outsider; without this passion ... you have no calling for science and you should do something else. For nothing is worthy of man as man unless he can pursue it with passionate devotion.