20. Geometry. Again the angle sculpture, introductory to the following series. We shall see presently why this science must be the foundation of the rest.
21. Sculpture.
22. Painting.
23. Grammar.
24. Arithmetic. The laws of number, weight, and measures of capacity.
25 Music. The laws of number, weight (or force), and measure, applied to sound.
26. Logic. The laws of number and measure applied to thought.
27. The Invention of Harmony.
You see now—by taking first the great division of pre-Christian and Christian arts, marked by the door of the Tower; and then the divisions into four successive historical periods, marked by its angles—that you have a perfect plan of human civilization. The first side is of the nomad life, learning how to assert its supremacy over other wandering creatures, herbs, and beasts. Then the second side is the fixed home life, developing race and country; then the third side, the human intercourse between stranger races; then the fourth side, the harmonious arts of all who are gathered into the fold of Christ.
Now let us return to the first angle, and examine piece by piece with care.