In the centre-piece, "The Adoration of the Lamb" (frontispiece), we discover the keynote to the scheme of the work, in the Apocalyptic Vision of St. John the source of its inspiration. The Lamb without spot, the blood from its breast pouring into a chalice, is stood on an altar, the white cloth over which bears on its superfrontal the text from the Vulgate, "Behold the Lamb of God, who taketh away the sins of the world," and on its stole-ends the legend, "Jesus, the Way, the Truth, and the Life." Worshipping angels gather around, some bearing instruments of the Passion, others swinging censers, their smoke laden with the prayers of the saints. In the foreground the Fountain of Life, flowing down through the ages along the gentle slope of flower-bejewelled sward, or dispensing its waters in vivifying jets from the gurgoyles beneath the feet and from the vases in the hands of the winged angel above its standard. To the four quarters groups of the elect: on the near right those of the Old Law and among the Gentiles who had lived in expectation of the Redeemer, the balancing group on the left typical of the New Law--prophets, doctors, philosophers, and princes in the former, the Apostles, popes, bishops, abbots, deacons, monks, and clerics among the latter. The corresponding groups back of the altar represent the army of martyrs whose blood is the seed of the Church, and the multitude of virgins. Over all, from the Holy Dove poised high over the altar, dart rays of light, emblematic of the Wisdom which had inspired their lives and of the fire of Love that had heartened their sacrifice. A carpet of flowers fills in all the open space fore of the altar, flowering shrubs and trees that of the mid-distance, while the entire background is an exquisite example of the realistic landscape-work that is an abiding charm of the Netherlandish school. The wonderful harmony of colour appeals at once to the senses; but more arresting, on nearer acquaintance, for its quality and felicity, is the wide range of portraiture that distinguishes the piece. From the two lateral panels in the dexter shutter the Knights of Christ and the Just Judges are pressing forward to the scene of the Vision, from the corresponding ones in the sinister shutter the Holy Hermits and the Holy Pilgrims: the former on spirited horses--an animal for which the painter evinces a special affection--the latter on foot. These panels are even more remarkable perhaps than the centre-piece for the diversity and multiplicity of the types portrayed, and for the wealth of landscape relieved by bird life lavished in their embellishment.