It is clear that the broad characteristics of the composition can be symmetrically expressed, so that a classification of the 70 S.C. altarpieces can be made on a basis of these constant elements, in the order of decreasing balance.  Thus:  Class 1, below, in which the C. is one side of the central line, turned away from the center, the M. turned to the other, balances in these broad lines, or I. + D. = D.; while in (9), I. + D. + D. = (x), the constant elements work all on one side.

CLASSIFICATION OF ALTARPIECES.

1 C. one side turned to same,  M. to other            11
2 "     "         "     other, "       "               8
3 "     "         "     front, "       "               2
4 "     "         "     other, M. front.               9
5 "     "         "     facing M.                      6
6 "     "         "     front, M. front.               7
7 "     "         "       "    M. turned to same.      6
8 "     "         "    to same M. turned front.        7
9 "     "         "       "    M.     "   to same,    14
10 " in middle, turned front.                           0

Thus the constant elements, understanding always that C. has more interest than M., are as follows:  For (1) I. + D. = D.; (2) I. = D. + D.; (3) I. = D.; (4) I. = D.; (5) I. + D. = D.; etc.  These are in order of complete balance, but it will be seen that from (7) on, while the factors are constant, the framework is not balanced; e.g. in (9) both I. and D. work on the same side.  For these groups, therefore, the variations, if there is balance, will be more striking.  Eliminating the balancing elements in the framework, the tables for the ten groups are: 

(1)  I. + D. = D.     (2)  I. = D. + D(M).   (3)  I. = D.
969.  I. = Ms.           680.  I. = D.        1094.  Ms. + I. = I. + D.
601.  I. = Ms.           735.  I. = D.          33.  I. = I. + D
49.  I. = Ms. + I.     1121.  I. = D.
634.  I. = Ms. + I.     1035.  I. = D.         (4)  I. = D.
584.  I. = I.            333.  I. = I. + D.    775.  I. = D.
686.  I. = I.             80.  I. = I. + D.    746.  I. = D.
794.  I. = D.            753.  I. = I. + D.   1106.  I. = Ms. + D.
164.  I. = D.           1114.  I. = D. + L.    781.  I. = Ms. + D.
368.  I. = D. + V.                           1131.  I. = I. + D.
927.  I. = V.                                 517.  I. = I. + D.
273.  I. = V.                                 327.  I. + Ms. = D. + V.
951.  I. + L. = D. + V.
715.  Unbalanced.

(5) I. + D. = D. (6) I. = (7) I. + D. =
43.  I. = I. 854.  I. = Ms. 725.  I. + D. = I. + L.
711.  I. = I. 1148.  I. = I. 206.  I. + D. = I. + L.
447.  I. = Ms. 709.  I. = D. 155.  I. + D. = D. + L.
643.  I. = Ms. 907.  I. = D. 739.  I. + D. = L.
777.  I. = Ms. + I. 586.  I. = Ms. + I. 331.  I. + D. = V.
637.  I. = Ms. + I. 137.  I. = Ms. + I. 980.  Unbalanced.
187.  Unbalanced.