A true Renaissance Man – humanist, priest, author, artist, architect, poet, priest, linguist, philosopher and cryptographer – Leon Battista Alberti (born: 1404, Genoa; died: 1472, Rome) was the first art theorist to write an exposition on the principles of perspective. Departing radically from the conventions of the Middle Ages, he emphasised, as Ian Chilvers, author of the The Oxford Dictionary of Art and Artists notes, “the rational basis of the arts, and the necessity for the artist to have a thorough grounding in such ‘sciences’ as history, poetry, and mathematics.”
Inspired by the mathematical order and beauty found in nature, Alberti set out rules of distance, dimension and proportion in his De Pictura or Della pittura (“On Painting”) of 1435, instructing painters on representation, composition, light and colour and encouraging them create elegant and visually pleasing works of art. He also makes a connection between morality and creativity. The book influenced several artists of the Italian Renaissance, among them Lorenzo Ghiberti, Fra Angelico and later, Leonardo da Vinci.
Here I quote from a 1956 translation of the book (by John R. Spencer) published by the Yale University Press.
On the size of quantities in human vision:
Here is a rule: as the angle within the eye becomes more acute, so the quantity seen appears smaller. From this it is clear why a very distant quantity seems to be no larger than a point. Even though this is so, it is possible to find some quantities and planes of which the less is seen when they are closer and more when they are farther away. The proof of this is found in spherical bodies. Therefore, the quantities, through distance, appear either larger or smaller. Anyone who understands what has already been said will understand, I believe, that as the interval is changed the extrinsic rays become median and in the same manner the median extrinsic. He will understand also that where the median rays are made extrinsic that quantity will appear smaller. And the contrary: when the extreme rays are directed within the outline, as the outline is more distant, so much the quantity seen will seem greater. Here I usually give my friends a similar rule: as more rays are used in seeing, so the thing seen appears greater; and the fewer the rays, the smaller.
On colour and light:
Shade makes colour dark; light, where it strikes, makes colour bright. The philosophers say that nothing can be seen which is not illuminated and coloured. Therefore, they assert that there is a close relationship between light and colour in making each other visible. The importance of this is easily demonstrated for when light is lacking colour is lacking and when light returns the colours return. […]
Through the mixing of colours infinite other colours are born, but there are only four true colours—as there are four elements—from which more and more other kinds of colours may be thus created. Red is the colour of fire, blue of the air, green of the water, and of the earth grey and ash. Other colours, such as jasper and porphyry, are mixtures of these. Therefore, there are four genera of colours, and these make their species according to the addition of dark or light, black or white. They are thus almost innumerable. We see green fronds lose their greenness little by little until they finally become pale. Similarly, it is not unusual to see a whitish vapour in the air around the horizon which fades out little by little (as one looks towards the zenith). We see some roses which are quite purple, others are like the cheeks of young girls, others ivory. In the same way the earth, according to white and black, makes its own species of colours.
Therefore, the mixing of white does not change the genus of colours but forms the species. Black contains a similar force in its mixing to make almost infinite species of colour. In shadows colours are altered. As the shadow deepens the colours empty out, and as the light increases the colours become more open and clear.
On the power of painting:
Painting contains a divine force which not only makes absent men present, as friendship is said to do, but moreover makes the dead seem almost alive. Even after many centuries they are recognized with great pleasure and with great admiration for the painter. Plutarch says that Cassander, one of the captains of Alexander, trembled through all his body because he saw a portrait of his King. Agesilaos, the Lacedaemonian, never permitted anyone to paint him or to represent him in sculpture; his own form so displeased him that he avoided being known by those who would come after him. Thus the face of a man who is already dead certainly lives a long life through painting. Some think that painting shaped the gods who were adored by the nations. It certainly was their greatest gift to mortals, for painting is most useful to that piety which joins us to the gods and keeps our souls full of religion. They say that Phidias made in Aulis a god Jove so beautiful that it considerably strengthened the religion then current.
On the function of a painter and the importance of good habits:
I say the function of the painter is this: to describe with lines and to tint with colour on whatever panel or wall is given him similar observed planes of any body so that at a certain distance and in a certain position from the centre they appear in relief, seem to have mass and to be lifelike. The aim of painting: to give pleasure, good will and fame to the painter more than riches. If painters will follow this, their painting will hold the eyes and the soul of the observer. We have stated above how they could do this in the passages on composition and the reception of light. However, I would be delighted if the painter, in order to remember all these things well, should be a good man and learned in liberal arts. Everyone knows how much more the goodness of a man is worth than all his industry or art in acquiring the benevolence of the citizens. No one doubts that the good will of many is a great help to the artist in acquiring both fame and wealth. It often happens that the rich, moved more by amiability than by love of the arts, reward first one who is modest and good, leaving behind another painter perhaps better in art but not so good in his habits. Therefore the painter ought to acquire many good habits—principally humanity and affability. He will thus have a firm aid against poverty in good will, the greatest aid in learning his art well.
Featured: The Hunt in the Forest by Paolo Uccello, Ashmolean Museum, Oxford, Wikimedia Commons