This text first of all tackles the territorial situation in the Middle Ages, the development and relevance of ecclesiastical structures in this period. It then goes on to present the subject, the genesis of the Christian medieval garden, investigating, beyond the external circumstances of the historical context, its genuine in-depth foundation, full of symbolic elements. The treatment of biblical sources, along with legendary archetypes developed in ancient times, will enable the keys governing its formal definition to be revealed. Myth and nature come forward in literature, painting and drawing, to reflect and bring back to life an ancestral iconography, in turn sustained by the Christian religion and its rules. The Spanish garden comes forward as a peculiar example of a blend of two models: Islamic and Christian.