he
reconstruction of the original is thus brought within sight.

Generally, it may be stated that the points of likeness determine and
classify all the examples of one custom or belief; the points of
unlikeness indicate the line of decay inherent in survivals.

This partial equation and partial divergence between different
examples of the same custom or belief allows a very important point to
be made in the study of survivals. We can estimate the value of the
elements which equate in any number of examples, and the value of the
elements which diverge; and by noting how these values differ in the
various examples we shall discover the extent of the overlapping of
example with example, which is of the utmost importance. A given
custom consists, say, of six elements, which by their constancy among
all the examples and by their special characteristics may be
considered as primary elements, in the form in which the custom has
survived. Let us call these primary elements by algebraical signs,
a, b, c, d, e, f. A second example of the same custom has
four of these elements, a, b, c, d, and two divergences, which
may be considered as secondary elements, and which we will call by the
signs g, h. A third example has elements a, b, and divergences
g, h, i, k. A further example has none of the primary elements,
but only divergences g, h, i, l, m. Then the statement of the case
is reduced to the following:--

1 = a, b, c, d, e, f.
2 = a, b, c, d + g, h.
3 = a, b + g, h, i, k.
4 = + g, h, i, l, m.

The first conclusion to be drawn from this is that the overlapping of
the several examples (No. 1 overlapping No. 2 at a, b, c, d,
No. 2 overlapping No. 3 at a, b + g, h, No. 3 overlapping No.
4 at + g, h, i) shows all these several examples to be but
variations of one original custom, example No. 4, though possessing
none of the elements of example No. 1, being the same custom as
example No. 1. Secondly, the divergences g to m mark the line of
decay which this particular custom has undergone since it ceased to
belong to the dominant culture of the people, and dropped back into
the position of a survival from a former culture preserved only by a
fragment of the people.[224]

The first of these conclusions is not affected by the order in which
the examples are arranged; whether we begin with No. 4 or with No. 1,
the relationship of each example to the others, thus proved to