Pierre Étienne Théodore Rousseau began painting landscapes when he was barely fourteen years old. Under the advice of his mother's cousin, the landscape painter Pau de Saint-Martin, in 1827 he entered Joseph Rémond's atelier, and in 1828 he was taught by Guillaume Lethière, both of them painters from the Académie. However, he soon turned away from the historical landscapes of his masters. In the Musée du Louvre, he copied works by Claude Lorrain, Adriaen van de Velde and Karel du Jardin, and he studied the work of John Constable. In 1829 he discovered the Woods of Fontainebleau and the following year he travelled to Auvergne, where he made his first sketches of wild nature.

Rousseau presented his compositions regularly at the Paris Salon from 1831 to 1836, the year when the jury refused his monumental Cows Coming Down, a work which was exhibited by the painter Ary Scheffer in his own atelier. Following his Parisian failure, that same year he moved to the small village of Barbizon, near the Woods of Fontainebleau. From then on, with the exception of his travels around France-but never to Italy-Rousseau alternated his sojourns in Paris and Barbizon, where he worked with Jules Dupré, Narcisse Diaz de la Peña, Jean-François Millet and other members of the so-called Barbizon School, of which he was the leader. Between 1836 and 1841 his paintings were systematically excluded from the Salons, which made him stop sending landscapes to the Parisian competitions until French artistic policy changed after the 1848 Revolution.

In the 1849 Salon, his painting Avenue of Trees, Forest of l'Isle-Adam received a first-class medal. However, he had to wait until 1852 to receive the long-awaited Cross of the Légion d'Honneur. In 1855 his landscapes were shown at the Paris Exposition Universelle in a room devoted entirely to him, which gave him some prestige. However, financial problems led him to give up some of his dearest works in public auctions held in 1850, 1861 and 1863. His economic situation did not improve until 1866, when the art dealers Brame and Durand-Ruel bought seventy of his paintings, presenting a complete retrospective of his oeuvre at the Cercle des Arts the following year.

Shortly before his death on 20 December 1867, Rousseau was honoured with the title of Officer of the Légion d'Honneur.

Juan Á. López-Manzanares