4.  It is not thus with us.  Why?  Because we incessantly move the ancient landmarks which our fathers have set. cf. Prov. xxii. 28.  We encroach, we add house to house, field to field, to enrich ourselves at the expense of our neighbour.  The great fish know the sojourning place that nature has assigned to them; they occupy the sea far from the haunts of men, where no islands lie, and where are no continents rising to confront them, because it has never been crossed and neither curiosity nor need has persuaded sailors to tempt it.  The monsters that dwell in this sea are in size like high mountains, so witnesses who have seen tell us, and never cross their boundaries to ravage islands and seaboard towns.  Thus each kind is as if it were stationed in towns, in villages, in an ancient country, and has for its dwelling place the regions of the sea which have been assigned to it.