William Burkitt on Revelation 8:10

The next judgment inflicted, or rather the farther progress of the former judgment, was the infecting of the waters and rivers with a mortal bitterness by a bitter star falling from heaven into them; denoting, some say, the fall of a great captain amongst the Jews in Judea; others understand it of heresy in general, of the Arian heresy in particular; and some apply it to the fall of Rome, the seat of the western empire; so Mr. Mede.

If it be understood of heresy, it shows us what a poisonous, bitter, and deadly nature, error and heresy is of. Error is as damnable as vice, the one is an open road, the other a by-path, to hell and destruction; and accordingly that person, and that people, which have a due care over their soul's salvation, will be as much afraid of erroneous principles as of debauched practices.