In the 14th and 15th books of the galenic work On the Usefulness of the Parts of the Body, dedicated to male and female reproductive organs and foetal development, the author presents nature (φύσις), the agent of the human body’s formation, as artistic and admirable, because it used an art (τέχνη) to make immortality possible, which consists in replacing one living being by another in an admirable way. Such an art is also related to a divine purpose, once nature’s action, possessing an intrinsic ability, is that of a demiurge. So, if, on the one hand, we have an artistic and practical nature, whose activity is proved by dissection and visible in the position and function of male and female reproductive organs, on the other, we have an abstract concept of the same nature, working to perpetuate humankind, but whose deepest and more abstract problems are not to be discovered nor solved in medical works such as On the Usefulness of the Parts of the Body. In this paper I will analyse how the concepts of φύσις and τέχνη relate to each other, by developing and deepening the role of nature as an artisan regarding the formation and function of the reproductive system and foetal development and its limits as such, pointing also the different subtleties of the concept.