"Hence the emblems of cruelty and craft, of courtesy and charity, embodied by certain creatures, personified by certain plants; hence the spiritual meanings attributed to precious stones, and to colours. And it may be added that in times of persecution, in the early Christian times, this hidden language enabled the initiated to hold communication, to give each other some token of kinship, some password which the enemy could not interpret. Thus, in the paintings discovered in catacombs, the Lamb, the Pelican, the Lion, the Shepherd, all meant the Son; the Fish _Ichthys_, of which the characters express the Greek formula: 'Jesus, Son of God, Saviour,' figures, in a secondary sense, the believer, the rescued soul, fished out from the sea of Paganism; the Redeemer having told two of His Apostles that they should be fishers of men. "And of course the period when human beings lived in closest intercourse with God--the Middle Ages--was certain to follow the revealed tradition of Christ, and express itself in symbolical language, especially in speaking of that Spirit, that essence, that incomprehensible and nameless Being who to us is God. At the same time it had at its command a practical means of making itself understood. It wrote a book, as it were, intelligible to the humblest, superseding the text by images, and so instructing the ignorant. This indeed was the idea put into words by the Synod of Arras in 1025: 'That which the illiterate cannot apprehend from writing shall be shown to them in pictures.' "The Middle Ages, in short, translated the Bible and Theology, the lives of the Saints, the apocryphal and legendary Gospels into carved or painted images, bringing them within reach of all, and epitomizing them in figures which remained as the permanent marrow, the concentrated extract of all its teaching." "It taught the grown-up children the catechism by means of the stone sentences of the porches," exclaimed Durtal. "Yes, it did that too. But now," the Abbe went on, after a pause, "before entering on the subject of architectural symbolism, we must first establish a distinct notion of what Our Lord Himself did in creating it, when, in the second chapter of the Gospel according to Saint John, He speaks of the Temple at Jerusalem, and says that if the Jews destroy it He will rebuild it in three days, expressly prefiguring by that parable His own Body. This set forth to all generations the form which the new temples were thenceforth to take after His death on the Cross. "This sufficiently accounts for the cruciform plan of our churches. But we will study the inside of the church later; for the present we must consider the meanings of the external parts of a cathedral.