During 1910-12, Lacasse intuitively established his search for light, extracted from the glistening rock. In 1925, Lacasse moved to Paris where he became known as a painter of religious scenes. However, with Brancusi as his neighbour, Lacasse was inspired to revisit his teenage interest in light and the composition of stone fragments which led him to make a series of small abstract paintings during the 1930s. His acquaintance with Robert Delaunay influenced his coloristic development.

Upon his return to Paris in 1946, after having spent the war years in Britain, Lacasse had been overshadowed by Serge Poliakoff, who admitted to having learnt much from him during the late 1930s during his visits to Lacasse's Montparnasse gallery 'l'Equipe'. The likeness between the work of the two painters has long been debated until An Jo FERMON published an essay in 2015.

The works of Lacasse are included in institutions and museums worldwide including: Musée d'Art Moderne de la Ville de Paris; Musée National d'Art; Moderne, Centre Pompidou, Paris; Musée des Beaux-Arts, Brussels; Musée de Tournai, Tournai; Musée des Arts Décoratifs, Paris; Tel Aviv Museum of Art, Tel Aviv; Eilat Museum, Eilat; Carnegie Institute, Pittsburgh; National Gallery of Victoria, Melbourne.