Cennino d'Andrea Cennini (c. 1360 – before 1427) was an Italian painter influenced by Giotto. He was a student of Agnolo Gaddi in Florence. Gaddi trained under his father, called Taddeo Gaddi, who trained with Giotto.Read about Cennino Cennini in Wikipedia
If you follow the course of one man through constant practice, your intelligence would have to be crude indeed for you not to get some nourishment from it. Then you will find, if nature has granted you any imagination at all, that you will eventually acquire a style individual to yourself, and it cannot help being good; because your hand and your mind, being always accustomed to gather flowers, would ill know how to pluck thorns.