Abstract: Diffusion motion is a common form of fluid motions. In this paper, by discussing the ancient Chinese poem "The fragrance of flowers touches the people as the messenger of the sudden warmth", we investigate the underlying physical mechanism of the diffusion phenomena of enchanting flower fragrance. By comparing the differences in concentrations of fragrance molecules, we find the Fick's law and the Peclet's number play essential roles in the principles of fluid diffusion. We then discuss the phenomena of diffusion in everyday life, as well as its various engineering applications.