Leonardo, from the town of Vinci to the West of Florence, was born in 1452 and died in 1519. He has been seen as a 'Renaissance Man' from Vasari onwards, but was closer in age to Perugino than to Michelangelo or Raphael. Vasari draws attention to his range of interests, including civil engineering, anatomy, practical jokes, optics, and experiments in oil and varnish. He was for Vasari the first of the painters of the final stage in the development of painting ( Vasari, Le Vite, Testo IV.8), and for Kugler, ed. Eastlake, Handbook of the History of Painting, Part One, The Italian Schools, First Edition, p. 175, 'his works are the first which afford complete satisfaction to the eye and the mind'.
He was a pupil of Andrea del Verrocchio, and it is claimed by Vasari that he painted the left hand angel of Verrocchio's Baptism of Christ (now in the Uffizi Gallery) and made it so much better than the figures of his master that Verrocchio refused to paint again because a child could paint better than he;Vasari's assumption of progress towards perfection makes this an inevitable refrain ( Vasari, Le Vite, Testo IV.19).
Leonardo, according to Vasari, had a reputation for beginning things but not finishing them, and, despite preparing, though not completing, a treatise on painting, as well as a reputation for failed technical experiments with his materials ( Vasari, Le Vite, Testo IV.33). Vasari summarises his contributions to art as being the introduction of a 'type of shadow to the manner of colouring in oils, which enabled the moderns to make figures which are lifelike in their relief... and a greater perfection in the anatomy of horses and of men' (see Vasari, Le Vite, Testo IV. 37: Life of Leonardo). Ruskin argues a case similar in its essentials (see Ruskin on Leonardo).