12 DOCUMENT 7 SEPTEMBER 1895 fessor of Natural History, and Heinrich Ganter (1848-1915), Professor of Mathe- matics, had also studied at the ETH.[15] Einstein took courses with all three and was especially fond of Mühlberg.[16] Einstein enrolled in the third year of the Gewerbeschule just after the third quarter of the school year had started.[17] He was younger than his fourteen classmates, who ranged in age from seventeen to nineteen, and he and his cousin Robert Koch, who enrolled in the Gymnasium soon afterward, were the only Jewish pupils in the school.[18] He completed his course work successfully (Doc. 10 lists courses and grades, and Appendix D outlines the contents of the curriculum) and passed his examinations in September 1896. Now he was eligible for admission to the ETH (see editorial note Matura Examinations at the Gewerbeschule, Aargau Kantonsschule). Einstein always retained a strong feeling of attachment to the Kantonsschule, recalling later: "Diese Schule hat durch ihren liberalen Geist und durch den schlichten Ernst der auf keinerlei äußerliche Autorität sich stützenden Lehrer einen unvergeßli- chen Eindruck in mir hinterlassen."[19] During his year in Aarau, Einstein lived in the home of Jost Winteler, a professor at the school. He developed close relationships with several members of the family and took part in family discussions, outings, and music sessions.[20] Even before coming to Aarau, Einstein had been thinking about the propagation of light waves through the ether (see Doc. 5). While there, he started to think about what would happen if one pursued a light ray at speeds approaching the velocity of light. In retrospect, he saw this problem as "das erste kindliche Gedanken- Experiment, das mit der speziellen Relativitätstheorie zu tun hat."[21] [15] See Mühlberg's and Ganter's obituaries in Tuchschmid 1916, pp. 61-86 and 87-97, respectively. [16] See Docs. 46 and 89. [17] The Kantonsschule academic year started in late April and ended early in the following April (see Aargau Programm 1895/96, p. 3). [18] See Aargau Programm 1895/96, pp. 14- 16. [19] Einstein 1955, p. 146. [20] See Doc. 18 and Anna Besso-Winteler to Edgar Lüscher. (See Lüscher 1944, p. 623, quoted in Doc. 11, note 1). [21] Einstein 1955, p. 146. 7. Albin Herzog to Gustav Maier [Zurich,] 25. IX. 1895. Herrn Gustav Maier, Zürich V. Auf Ihre Anfrage vom 24. ds. teile ich Ihnen folgendes mit: Nach meiner Erfahrung ist es nicht empfehlenswert, auch sogenannte "Wunderkinder" vor der gänzlichen Absolvirung einer Anstalt, in der einmal die Studien be–