AGLIONBY, William, Painting Illustrated in Three Diallogues. Containing some Choice Observations upon the Art. Together with The Lives of the Most Eminent Painters From Cimabue, to the time of Raphael and Michael Angelo. With an Explanation of the Difficult Terms, London, John Gain, 1685.1 quotations
When a Painter has acquired any Excellency in Desinging, readily and strongly ; What has he to do next ?
That is not half his Work, for then he must begin to mannage his Colours, it being particularly by them, that he is to express the greatness of his Art. ’Tis they that give, as it were, Life and Soul to all that he does ; without them, his Lines will be but Lines that are flat, and without a Body, but the addition of Colours makes that appear round ; and as it were out of the Picture, which else would be plain and dull. ’Tis they that must deceive the Eye, to the degree, to make Flesh appear warm and soft, and to give an Air of Life, so as his Picture may seem almost to Breath and Move. [...] Friend,
Wherein particularly lies the Art of Colouring ?
Beside the Mixture of Colours, such as may answer the Painter’s Aim, it lies in a certain Contention, as I may call it, between the Light and the Shades, which by the means of Colours, are brought to Unite with each other ; and so to give that Roundness to the Figures, which the Italians call Relievo, and for which we have no other Name : In this, if the Shadows are too strong, the Piece is harsh and hard, if too weak, and there be too much Light, ’tis flat.