The first on the right is the mantle of St. Cecilia; others are the bodice of St. Agnes, St. Stephen's robe, a prophet's tunic; and above these, before reaching the lapis-lazuli border of sky, the robe of the first angel.
Thus blue, which is the predominating colour in the whole, is regularly piled up in steps and spaced almost identically on the opposite sides of the throne. This azure hue of the draperies, their folds faintly indicated with white, is extraordinarily serene, indescribably innocent. This it is which gives the work its soul of colour—this blue, helped out by the gold which gleams round the heads, runs or twines on the black robes of the monks; in Y's on those of St. Thomas; in suns, or rather in radiating chrysanthemums, on those of St. Antony and St. Benedict; in stars on St. Clara's hood; in filagree embroidery in the letters of their names, in brooches and medallions on the bodices of the other female saints.
At the very bottom of the picture a splash of gorgeous red—the Magdalen's robe—that finds an echo in the flame-colour of one of the steps of the throne, and reappears here and there, but softened in fragmentary glimpses of drapery, or smothered under a running pattern of gold (as in St. Augustine's cope) serves as a spring-board, as it were, to start the whole stupendous harmony.
The other colours seem to fill no part, but that of necessary stop-gaps, indispensable supports. They are too, for the most part, common and ugly to a degree that is most puzzling. Look at the greens: they range from boiled endive to olive, ending in the absolute hideousness of two steps of the throne which lie across the picture—two bars, two streaks of spinach dipped in tawny mud. The only tolerable green of them all is that of St. Agnes' mantle, a Parmigiano green, rich in yellow, and made still richer by the lining which affords the pleasing adjunct of orange.
On the other hand, consider this blue which Angelico uses so sumptuously in his celestial tones; when he makes it darker it loses its fulness, and looks almost dull; we see this in St. Clara's hood.
But what is yet more amazing is that this painter, so eloquent in blue, is but a stammerer when he makes use of the other angelic hue—rose-pink. In his hands it is neither subtle nor ingenuous; it is opaque, of the colour of blood thinned with water, or of pink sticking-plaister, excepting when it trends on the hue of wine-lees, like that of the Saviour's sleeves.
And it is heaviest of all in the saints' cheeks. It looks glazed, like the surface of pie-crust; it has the quality of raspberry syrup drowned in white of egg.
These are in the main the only colours used by Angelico. A magnificent blue for the sky and another vile blue, white, brilliant red, melancholy pinks, a light green, dark greens, and gold. No bright yellow like everlastings, no luminous straw-colour; at most a heavy opaque yellow for the hair of his female saints; no truly bold orange, no violet, either tender or strong, unless in the half-hidden lining of a cloak or in the scarcely visible robe of a saint, cut off by the frame; no brown that does not lurk in the background. His palette, as may be seen, is very limited.
And it is symbolical, if we consider it. He has undoubtedly done in his hues what he has done in the arrangement of the work. His picture is a hymn to Chastity, and round the central group of Christ and His Mother he has placed in ranks the Saints who best concentrated this virtue on earth. St. John the Baptist, beheaded for the bounding impurity of an Herodias; St. George, who saved a virgin from the emblematic Dragon; such saints as St. Agnes, St. Clara, and St. Ursula; the heads of the Orders—St. Benedict and St. Francis; a king like St. Louis, and a bishop like St. Nicholas of Myra, who hindered the prostitution of three young girls whom a starving father was fain to sell. Everything, down to the smallest details, from the attributes of the persons represented to the steps of the throne, of which the number is nine—that of the choirs of angels—everything in this picture is symbolical.
It is permissible therefore to assume that he selected his colours for their allegorical signification.