The word Renaissance is used for the art which developed in the XV and XVI centuries and was used for the first time in 1860 by Jacob Burckardt in his publication “Renaissance civilisation”. Before this date Giorgio Vasari used the word ‘rebirth’ to describe the changes and the innovation which took place starting from the XIV century. A unique feature of the Renaissance was the interest in all cultural expressions of the past; Renaissance artists felt bound to the classical age and considered the Middle Ages an age of decadence. Art focussed on the classical ages did not simply imitate but started from the classical age models to create new art. Many artists went to Rome to study classical masterpieces whereas Florence was very important because many families commissioning works of art, in particular the Medici family. Classical art is nature-oriented and aimed at imitating nature. Therefore in this period the study of the natural world increased considerably. The result of these studies was a different way of analysing the surrounding world, as shown by the discovery of perspective and proportions. Some artists wrote treatises on the topic, such as Leon Battista Alberti’s De Pictura, finished in 1453. Another example is Piero della Francesca, who wrote De prospectiva pingendi.