In the 1940s, Yves Klein was beginning to shape his artistic vision, though his most influential work would come later. Born in 1928 into an artistic family, Klein grew up surrounded by art and culture, which profoundly influenced his development as an artist. Despite this rich environment, Klein received no formal artistic training during his early years​ (The Art Story)​. His early life in Nice, France, and subsequent travels, including his time in Japan and London, played a crucial role in his artistic and personal development. By the late 1940s, Klein began experimenting with what would become his signature style and approach to art. He had not yet developed the iconic International Klein Blue (IKB) or his famous monochrome paintings; these would come in the late 1950s. However, the period was marked by significant experiences that would shape his future work, such as his division of the universe with friends Claude Pascal and Arman Fernandez in 1947, where Klein famously chose "the void" or the sky as his domain. This act was symbolic of Klein's lifelong pursuit to capture the infinite and the immaterial, laying the groundwork for his later work​ (The Art Story)​. Klein's early artistic experiments were also influenced by his deep dive into Eastern philosophies and martial arts, particularly judo, which he studied in Japan. This exposure to different cultural perspectives and practices further informed his approach to art, emphasizing themes of emptiness, space, and the immaterial​ (The Art Story)​. It was also reported that in the 1940s, Klein began his explorations with monochrome paintings, particularly using ultramarine, a vivid blue pigment. Dissatisfied with the pigment's tendency to fade, Klein's experiments eventually led him to develop the unique International Klein Blue in the mid-1950s, which became a central element of his artistic identity​ (Mental Floss)​. Thus, while the 1940s may not have seen Klein at the height of his artistic career, they were formative years in which he laid the foundation for his later, more famous works. His experiences during this decade reflect a period of exploration and conceptual development, setting the stage for the groundbreaking contributions to modern art that would follow​ (The Art Story)​​ (Mental Floss)​.