White: the symbol of the Supreme Being, and of absolute Truth, and employed by the Church in its adornments for the festival of our Lord and the Virgin because it signifies Goodness, Virginity, Charity, and is the splendour, the
emblem of Divine Wisdom when it is enhanced to the pure radiance of silver.
Blue: because it symbolizes Chastity, Innocence, and Guilelessness.
Red: which is the colour adopted for the offices of the Holy Ghost and of the Passion; the garb of Charity, Suffering and Love.
Rose-pink; the Love of Eternal Wisdom, and, as Saint Mechtildis teaches, the anguish and torments of Christ.
Green: used liturgically at Seasons of Pilgrimage, and which seems to be the colour preferred by the Benedictine Sisterhood, interpreting it as meaning freshness of soul and perennial sap; the green which, in the hermeneutics of colour, expresses the hopes of the regenerated creature, the yearning for final repose, and which is likewise the mark of humility, according to the Anonymous English writer of the thirteenth century, and of contemplation, according to Durand of Mende.
On the other hand, Angelico has intentionally refrained from introducing the hues which are emblematic of vices, excepting of course those adopted for the garb of the Monastic Orders, which altogether changes their meaning.
Black: the colour of error and the void, the seal of death, and, according to Sister Emmerich, the image of profaned and wasted gifts.
Brown: which, as the same Sister tells us, is synonymous with agitation, barrenness and dryness of the spirit, and neglect of duty; brown; which being composed of black and red—smoke darkening the sacred fire—is Satanic.
Grey: the ashes of penance, the symbol of tribulation, according to the Bishop of Mende, the sign of half-mourning formerly used in the Paris ritual instead of violet in Lent. The mingling of white and black, of virtue and vice, of joy and grief, the mirror of the soul that is neither good nor evil, the medium being, the lukewarm creature that God spueth out, grey can only rise by the infusion of a little purity, a little blue; but can, when thus converted to pearl grey, become a pious hue, and attempt a step towards Heaven, an advance in the lower paths of Mysticism.