John Ruskin 
Mornings in Florence [EPUB ebook] 

If there is one artist, more than another, whose work it is desirable that you should examine in Florence, supposing that you care for old art at all, it is Giotto. You can, indeed, also see work of his at Assisi; but it is not likely you will stop there, to any purpose. At Padua there is much; but only of one period. At Florence, which is his birthplace, you can see pictures by him of every date, and every kind. But you had surely better see, first, what is of his best time and of the best kind. He painted very small pictures and very large-painted from the age of twelve to sixty-painted some subjects carelessly which he had little interest in some carefully with all his heart. You would surely like, and it would certainly be wise, to see him first in his strong and earnest work, -to see a painting by him, if possible, of large size, and wrought with his full strength, and of a subject pleasing to him. And if it were, also, a subject interesting to yourself, -better still.
Now, if indeed you are interested in old art, you cannot but know the power of the thirteenth century. You know that the character of it was concentrated in, and to the full expressed by, its best king, St. Louis. You know St. Louis was a Franciscan, and that the Franciscans, for whom Giotto was continually painting under Dante’s advice, were prouder of him than of any other of their royal brethren or sisters. If Giotto ever would imagine anybody with care and delight, it would be St. Louis, if it chanced that anywhere he had St. Louis to paint.