The beginning of his career in Switzerland was unpromising: during his first semester of teaching, he had only ten students, and he himself said that the income he received from his private practice was insufficient to pay for his morning cup of coffee.

Students flocked to his lectures, and with the cooperation of energetic colleagues, he was able to raise the Medical Faculty of Zurich to a prominent position among German speaking schools in only a few years.

[3] Though he laid the foundation of his fame at Zurich, it was in Vienna, a larger and more conspicuous theater, that he established himself as the power that he was in the surgical world.

[2] A speech he gave in 1875, protesting influxes of Jewish medical students, has been counted as one of the first events in the development of Viennese political anti-Semitism.

[3][2] His treatise on wound fever, Untersuchungen über die Vegetationsformen von Coccobacteria septica (1874; “Investigations of the Vegetal Forms of Coccobacteria septica”) concluded that the cause was bacterial; Billroth was quick to use antiseptic techniques in his surgical practice, and the number of surgical patients afflicted with wound fever greatly decreased.

With the threat of fatal surgical infections lessened through his work and others’, Billroth proceeded to turn his attention to surgery and the pioneering field of altering or removing organs that had previously been considered inaccessible.

[2] An early adopter of the "white coat" (as shown in Seligmann's c.1890 painting),[5] Billroth was directly responsible for a number of landmarks in surgery; in 1872, he was the first to conduct an esophagectomy, removing a section of the oesophagus and joining the remaining parts together.

[8] On January 29, 1881, after many ill-fated attempts, Billroth performed the first successful resection for antral carcinoma on Therese Heller, who lived for almost 4 months and died of liver metastases.

To this, Billroth contributed the section on Scrofulosis and Tuberculosis, Injuries and Diseases of the Breast, Instruments and Operations, Burns, Frostbites, etc.

In all the spheres he sought to influence, he was guided by a belief in the unity of science and art, and by confidence in his own ability to effect change.

During his time in Zurich he regularly played string quartet with professional musicians such as Theodor Kirchner and Friedrich Hegar.

In 1865 he met Brahms for the first time when the rising composer and pianist played Robert Schumann's piano concerto and his own works in Zurich.

In the essay, Billroth identifies different types of amusicality (tone deafness, rhythm-deafness and harmony-deafness) that suggest some of the different cognitive skills involved in the perception of music.