"... Suppose a large number of values, subject to variations on either side of a , and suppose these variations bound by no common law. Then, if a sufficiently large number of such values are taken into consideration, it will be found that the variations on either side of the mean value will counterbalance one another. If, then, we regard the absolute motions of the stars as subject to no common law, i.e., if we suppose the stars to be pursuing their courses independent of any common , and if a very large number of s are taken together, if would follow from this principle, that in the aggregate the peculiar proper motions would cancel one another, and the mean result would be unaffected by them and would give only the . This method of treatment, based upon the , is called the method of "," and is of wide application ..."