Indeed, little Louis grew up watching his father engage in these activities, so it was no surprise that one of his first demonstrations of artistic talent appeared early, in 1836, when he paint a portrait of the famous military figure at school.

In an time when French national educational programs placed great importance on drawing, his teacher encouraged him to continue. One of the first portraits he did using pastel technique was of his mother (which can be seen on the cover of "The Pasteurian").

Jeanne-Étiennette Roquide, Louis Pasteur's mother (portrait painted by the scientist in 1836).

Although his father tried to send him to Paris to focus on studies unrelated to art, Louis continued to develop his artistic skills by portraying friends and acquaintances from his hometown. When he entered the Royal College of Besançon at the age of 16, he had already gained some recognition as a portraitist among other students and teachers, receiving various commissions. By then, his works showed certain hints of Romanticism, influenced by his admiration for the poetry of Lord Byron and Alphonse de Lamartine. While at the college, Louis had his most notable year in his artistic career in 1841, when he began experimenting with lithography, a printing technique on stone for which artists like Eugène Delacroix and Théodore Géricault were already well-known.

A year later, prior to his enrollment in the prestigious École Normale Supérieure in Paris, the young man obtained his high school diploma in science and mathematics, notably receiving a 'mediocre' grade in chemistry. He also stopped using pastels and experimented with other techniques. His last pastel portrait was of his father, who was now more pleased with the scientific path his son had begun to pursue.

Jean-Joseph Pasteur, Louis Pasteur's father (portrait painted by the scientist in 1842). Between the ages of 13 and 20, Louis Pasteur created over 40 portraits of men and women from the 19th century.

Over time, science drew Louis away from painting, but in 1863, when he was already a renowned scientist, he returned to the art world when he was invited to teach at the École des Beaux-Arts in Paris. There, he was able to merge his scientific vocation with his artistic passion by teaching painters the secrets of color preservation, advising master restorers at the Louvre Museum on issues related to the drying and aging of varnishes, and even studying the chemical formula of a drying agent used in oil paints, where he identified significant drawbacks due to its lead content.

In 1867, while preparing to develop a new drying agent, he resigned from his teaching position to dedicate himself to researching the silk worm disease, which was severely affecting the production of this natural fiber in France. Science still held many secrets for him to uncover. Just a few years earlier, in 1864, Pasteur had introduced the revolutionary process of pasteurization to the world, but it would be another 20 years before he drove another fundamental change in science: the development of vaccines.

Regarding Pasteur and art, the painter Albert Edelfelt, who created the famous portrait of the scientist in his laboratory, wrote in a letter to a friend:

"When Louis was 16 years old, he had attempted to become a painter and would spend his time creating pastel portraits of the citizens of Arbois. Some of these paintings can be found in his home or at the institute. I have observed them frequently, and they are extremely good and superior to the usual work of young people pursuing an artistic career. There is something of the great researcher in these portraits: they express absolute truth and an uncommon willpower. I am sure that if Pasteur had chosen art instead of science, France would today have one of its most capable painters."

Portrait of Louis Pasteur in his laboratory, by Albert Edelfelt (1885).