The Bear, the Louse, and Religion

I should be much obliged to any of your correspondents who will inform me where I can find *The Bear, the Louse, and Religion*: a fable. It commences— "A surly Bear, in college bred, Determin'd to attack Religion; A Louse, who crawl'd from head to head, Defended her—as Hawk does pidgeon. Bruin Subscription discommended; The Louse determin'd to support it—" I know no more. When was it written?—upon what occasion?—who are meant by the Bear and the Louse?