The optical illusions that present themselves on the sea-shore, by which distant objects are raised to view, the opposite capes and islands made to loom up, lifted above the line of the apparent circumference of the earth, and thrown into every variety of shape which the imagination can conceive, are among the most beautiful phenomena of nature; and they impress the mind with the idea of enchantment and mystery, more perhaps than any others: but they have received a complete solution from modern discovery. It should be observed, that the optical principles which explain these phenomena have recently afforded a foundation for the science, or rather art, of nauscopy; and there are persons in some places,—in the Isle of France, as I have been told,—whose calling and profession is to ascertain and predict the approach of vessels, by their reflection in the atmosphere and on the clouds, long before they are visible to the eye, or through the glass. The following opinion prevailed at the time of our narrative. The discoveries in electricity, itself a recent science, have rendered it impossible for us to contemplate it without ridicule. But it was the sober[i.387] opinion of the age. "A great man has noted it," says a learned writer, "that thunders break oftener on churches than any other houses, because demons have a peculiar spite at houses that are set apart for the peculiar service of God." Every thing that was strange or remarkable—every thing at all out of the usual course, every thing that was not clear and plain—was attributed to supernatural interposition. Indeed, our fathers lived, as they thought, continually in the midst of miracles; and felt themselves surrounded, at all times, in all scenes, with innumerable invisible beings. The beautiful verse of Milton describes their faith:— "Millions of spiritual creatures walk the earth Unseen, both when we wake and when we sleep." What was to him, however, a momentary vision of the imagination, was to them like a perpetual perception of the senses: it was a practical belief, an everyday common sentiment, an all-pervading feeling. But these supernatural beings very frequently were believed to have become visible to our superstitious ancestors. The instances, indeed, were not rare, of individuals having seen the Devil himself with their mortal eyes. They may well be brought to notice, as illustrating the ideas which then prevailed, and had an immediate, practical effect on the conduct of men, in reference to the power, presence, and action of the Devil in human affairs. This, in fact, is necessary, that we may understand the narrative we are preparing to contemplate of transactions based wholly on those ideas.[i.388] The following passage is extracted from a letter written to Increase Mather by the Rev. John Higginson:—