Huygens is known among Physics introductory teaching for his study on refraction through a wave model. Didactic books honor him by giving his name to a principle. But in his masterpiece, Treatise on Light, it is possible to notice much more: his inventiveness in defending an alternative wave model of light in opposition to the corpuscular model. This work attempts to highlight Huygens' reasoning, showing that, despite having been published more than three hundred years ago, the work is written in a relatively accessible language.