In 1808, he was appointed physician to the Lycée Impérial in Liège, which opened many doors for him, including the post of president of the medical jury for the Ourthe department.

He returned as rector between 1829 and 1830, but lost his position in 1835 following a reshuffling of teaching duties, probably due to his Orangism background.

He completed his secondary education at the Collège de Visé, then run by the Congregation of the Oratory of Jesus and Mary Immaculate.

[Notes 2][3][4] During his time in France, he had the opportunity to interact with numerous individuals who would later play a role in the French Revolution, including Joseph Fouché, with whom he developed a close relationship, and Maximilien de Robespierre.

[5] Faced with the possibility of a challenging situation, particularly the potential impact on educational institutions run by religious communities, Toussaint-Dieudonné Sauveur began studying medicine in Paris[6] between 1789 and 1792.

[7] Moreover, the invasion of the Netherlands by the Austrian army led to a disruption in his family's ties and a loss of financial resources.

[Notes 4][12] The previous year, he had been commissioned by the king, along with Nicolas-Gabriel Ansiaux and Charles Delvaux de Fenffe, to create the Belgian pharmacopeia.

[13][14] During this period, he was a member of the "commission charged by the government with examining and revising the laws, decrees, and regulations previously promulgated on the practice of the healing art",[17] leaving a lasting impact on medicine and academia.

[19][20] Trained in the disciplines of the Lumières, the first teachers were full of praise for King William, and their situation was much better than under the Ourthe prefects.

[21] Trained by the Oratorians, a congregation "composed of men without intrigue or desire for domination," he feared seeing "the pontifical see enter the throne of Belgium" and the "militias of Rome.

"[19][21] In 1835, following a reorganization of teaching duties, Toussaint-Dieudonné Sauveur was relieved of his professorship, which caused him significant distress.

The eldest, Dieudonné-Jean-Joseph Sauveur (1797–1862), was also a doctor but subsequently pursued an administrative career in Brussels, ultimately becoming Inspector General of the Civil Health Service.

[28] He was appointed a member of the Société médicale d'émulation de Paris at the recommendation of Professor Paul-Joseph Barthez.

[29] One of his mottos, attributed to Ludwig Gottfried Klein (de), is "I am no more attached to ancient physicians than to modern ones; I use both indifferently when they follow the truth: an often-repeated experience is my main guide.