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'.

During her lifetime, Sonia Delaunay defended Lacasse as the precursor of Poliakoff in her correspondance, kept at the Kandinksy Library in Paris. However, it took decades and the publication of an essay by art historian An Jo Fermon in 2015, to reposition Lacasse in his rightful place within the Western art historical canon.

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; Tel Aviv Museum of Art, Tel Aviv; Eilat Museum, Eilat; Carnegie Institute, Pittsburgh; National Gallery of Victoria, Melbourne; Musée des Arts Décoratifs, Paris.