The great number of alterations of stars that we are certain have
happened within the last two centuries, and the much greater number
that we have reason to suspect to have taken place, are curious
features in the history of the heavens, as curious as the slow
wearing away of the landmarks of our earth on mountains, on river
banks, on ocean shores. If we consider how little attention has
formerly been paid this subject, and that most of the observations
we have are of a very late date, it would perhaps not appear
extraordinary were we to admit the number of alterations that have
probably happened to different stars, within our own time, to be a
hundred.
--_William Herschel_