A common mode of thought in the Middle Ages was to draw an analogy between a microcosm and macrocosm. The illustration shows a man drawn within a square marked with the signs of the zodiac.
In Shakespeare's Richard II, Act 3 Scene 4, the king's neglect the garden of England is compared with the care of his own garden.
Illustrations of this type were used in many editions of Vitruvius and Leonardo da Vinci was fascinated by them.
Rudolf Wittkower discusses their significance in his 1949 book on Architectural principles in the age of humanism. Vitruvius 'had introduced his third book on Temples with the famous remarks on the proportions of the human figure, which should be reflected in the proportions. As a proof of the harmony and perfection of the human body he described how a well-built man fits with extended hands and feet exactly into the most perfect geometrical figures, circle and square. This simple picture seemed to reveal a deep and fundamental truth about man and the world, and its importance for Renaissance architects can hardly be overestimated. The image haunted their imagination'. (1988 Academy Editions p 22)
Medieval art, architecture and society were saturated with religion and infused with symbols. A simple garden, of the type in which Augustine's conversion took place, in saintly contrast with the luxurious gardens and grottoes of pagan debauchery.