Before he left for Paris in 1919, Xu Beihong was surrounded by a societal atmosphere focused on anti-feudalism and the advocacy for reform. During his period in the capital, Xu made the acquaintance of major figures in the reform movement such as Li Shizeng and Cai Yuanpei. Heavily influenced by the ideas surrounding the New Culture Movement, he helped established new trends encouraging the pursuit of democracy and science, firmly believing that a new China could be established on the basis of those two factors. For these reasons, during his travels and studies in France and Europe, he gave special attention to Realism, as it followed the principles of natural science. He also devoted great energy to researching the art of academic traditions from the Renaissance, searching for principles that had guided classical art in depicting proportion and shaping of forms. But in fact, it was precisely in the 1920s that the trend toward non-figurative and abstract styles of art was sweeping through Paris. Broad discussion took place regarding both the traditional French realist styles and the Paris School, which under the influence of foreign artists residing in Paris, employed styles that tended toward the non-figurative. The fact that these general trends toward Cubism, non-figurative art, and abstract art were present in the background shows that Xu Beihong's choice of a realist style was a very deliberate one. He believed that the objective spirit behind realism would be more understandable to the masses of people in China at that time who had little knowledge or background to allow an understanding of Western art, and thus realism could help achieve the goals of art education and popularizing art. Lin Fengmian, however, who also traveled to Paris in 1919, chose to focus on new trends in art such as Cubism and Fauvism, and his work would later serve to nurture future abstract artists in China.
Xu Beihong spend his time in Europe actively training himself in the fundamentals of realist painting, and after gaining admission to the Ecole Nationale Superieure Des Beaux-arts, he further supplemented his training in sketching at the Academie Julian, and systematically acquired an understanding of basic painting techniques such as perspective, chiaroscuro, bounded lines, naturalistic colour, and compositional harmony. In addition to his academic training, Xu made detailed studies of famous works, and engaged in long periods of observation to ensure accurate portrayal of his subjects. During a short stay in Berlin in 1921, he spent every clear day painting either at the museum or the zoo, and once, just to accurately capture the way a lion raises its rear leg when walking, he spent three months sketching lions at the zoo. Xu said, "During my stay in Paris and Berlin, I went to their zoos, where they raised lions and bears. I made separate sketches of each on their own, many times. I think lions and bears have personalities too." Xu gradually acquired a very strong penchant for sketching animals, and in his depictions they take on strong personalities. Current information indicates that his sketches of animals included lions, eagles and pines, black chickens, and horses.
Eagles (Lot 22) depicts two birds soaring high in a blue sky. Xu Beihong applies thin layers of colour with a stiff bristle brush, giving great attention to the application of various shades of blue to present the subtle changes in the sky. Xu further employs classical realist oil techniques to add multiple washes of colour, building colour one layer at a time in conformance with his shapes and forms. Beyond his painstakingly detailed depiction of their forms, Xu also attends to the expressions of the eagle and the dove. The eagle's wings are spread as he bends into a dive, his talons extended powerfully and ready to grasp his prey, while his fierce gaze expresses both determination and confidence in the hunt. The mild and gentle dove, on the other hand, is facing a fierce opponent but nevertheless refuses to panic, and remains determined and gives its last effort at survival. Xu's painting both portrays the way of survival in the natural world and serves as a metaphor for the spirit of strength and determination when facing a powerful foe. At the same time, it documents the history of self-strengthening and reform in China as the first student who participated in the Work-study program in France at the beginning of the 20th century.