In Modern Painters I Ruskin 's view of Giotto still shows some traces of the influence of Vasari 's belief in the progress of art towards the perfection of Michelangelo, at MP I:9, for example, and in his reference to Byzantine schools.
Ruskin later agreed that Giotto laid the foundations of Christian art and architecture:
The entire system of possible Christian Art is founded on the principles established by Giotto in Florence, he receiving them from the Attic Greeks though Cimabue, the last of their disciples, and engrafting them on the existing art of the Etruscans, the race from which both his master and he were descended. ( Works, 15.344)
However, in opposition to Vasari, Ruskin came to argue that Giotto 's work was not merely the first stage, but represented a fully achieved excellence (compare Vasari on Giotto). Giotto's Campanile for Florence Cathedral is described as the most perfect work of Christian architecture, and the 'art of Giotto and Angelico is not taught because it is Christian but because it is absolutely true and good' ( Works, 15.344).
Ruskin writes at Works, 23.322 that Giotto looked at things as they were, and directly challenges the conventional distinction between Florentine and Venetian schools which saw the Venetians, not the Florentines as the masters of colour:
Giotto threw aside all the glitter, and all the conventionalism, and declared that he saw the sky blue, the tablecloth white, and angels, when he dreamed of them, rosy, and he simply founded the schools of colour in Italy -- Venetian and all... And what is more, nobody discovered much about colour after him.
Similarly at Works, 13.525 the lessons given by Giotto, together with Botticelli and Fra Angelico were 'conclusive' on the relationship between line and colour.
At Works, 23.333 Giotto looked not only at things but also at people as they were: 'he defines, explains, and exalts every sweet incident of human nature'. Giotto 'came from the fields' and he painted the Holy Family as 'Mamma, Papa, and the Baby'.