“Prognostics do not always prove prophecies, — at least the wisest prophets make sure of the event first.”

Not found in Addison's works, and "Jesters do oft prove prophets" is actually William Shakespeare, in King Lear, Act V, sc. iii.
Misattributed

Vol. II, Ch. 1 : Introduction, concerning the time when the Apocalypse was written
Observations upon the Prophecies of Daniel, and the Apocalypse of St. John (1733)
Context: The folly of Interpreters has been, to foretell times and things by this Prophecy, as if God designed to make them Prophets. By this rashness they have not only exposed themselves, but brought the Prophecy also into contempt.
The design of God was much otherwise. He gave this and the Prophecies of the Old Testament, not to gratify mens curiosities by enabling them to foreknow things, but that after they were fulfilled they might be interpreted by the event, and his own Providence, not the Interpreters, be then manifested thereby to the world. For the event of things predicted many ages before, will then be a convincing argument that the world is governed by providence. For, as the few and obscure Prophecies concerning Christ’s first coming were for setting up the Christian religion, which all nations have since corrupted; so the many and clear Prophecies concerning the things to be done at Christ’s second coming, are not only for predicting but also for effecting a recovery and re-establishment of the long-lost truth, and setting up a kingdom wherein dwells righteousness. The event will prove the Apocalypse; and this Prophecy, thus proved and understood, will open the old Prophets, and all together will make known the true religion, and establish it. For he that will understand the old Prophets, must begin with this; but the time is not yet come for understanding them perfectly, because the main revolution predicted in them is not yet come to pass. In the days of the voice of the seventh Angel, when he shall begin to sound, the mystery of God shall be finished, as he hath declared to his servants the Prophets: and then the kingdoms of this world shall become the kingdom of our Lord and his Christ, and he shall reign for ever, Apoc. x. 7. xi. 15. There is already so much of the Prophecy fulfilled, that as many as will take pains in this study, may see sufficient instances of God’s providence: but then the signal revolutions predicted by all the holy Prophets, will at once both turn men’s eyes upon considering the predictions, and plainly interpret them. Till then we must content ourselves with interpreting what hath been already fulfilled.
Amongst the Interpreters of the last age there to scarce one of note who hath not made some discovery worth knowing; and thence I seem to gather that God is about opening these mysteries. The success of others put me upon considering it; and if I have done any thing which may be useful to following writers, I have my design.

An Agricultural Testament, Oxford University Press, 1943, Part V, Chapter 15. Full text online http://ps-survival.com/PS/Agriculture/An_Agricultural_Testament_1943.pdf.

H 23
Aphorisms (1765-1799), Notebook H (1784-1788)

Watch Tower, (October 1890), p. 8.

Summer, § VII, p. 89
The Private Papers of Henry Ryecroft (1903)
Context: This writer, who is horribly perspicacious and vigorous, demonstrates the certainty of a great European war, and regards it with the peculiar satisfaction excited by such things in a certain order of mind. His phrases about "dire calamity" and so on mean nothing; the whole tenor of his writing proves that he represents, and consciously, one of the forces which go to bring war about; his part in the business is a fluent irresponsibility, which casts scorn on all who reluct at the "inevitable." Persistent prophecy is a familiar way of assuring the event.

Vol. I, Ch. 2: Of the Prophetic Language
Observations upon the Prophecies of Daniel, and the Apocalypse of St. John (1733)
Context: For understanding the Prophecies, we are, in the first place, to acquaint our-selves with the figurative language of the Prophets. This language is taken from the analogy between the world natural, and an empire or kingdom considered as a world politic. Accordingly, the whole world natural consisting of heaven and earth, signifies the whole world politic, consisting of thrones and people, or so much of it as is considered in the Prophecy: and the things in that world signify the analogous things in this. For the heavens, and the things therein, signify thrones and dignities, and those who enjoy them; and the earth, with the things thereon, the inferior people; and the lowest parts of the earth, called Hades or Hell, the lowest or most miserable part of them. Whence ascending towards heaven, and descending to the earth, are put for rising and falling in power and honor: rising out of the earth, or waters, and falling into them, for the rising up to any dignity or dominion, out of the inferior state of the people, or falling down from the same into that inferior state; descending into the lower parts of the earth, for descending to a very low and unhappy estate; speaking with a faint voice out of the dust, for being in a weak and low condition; moving from one place to another, for translation from one office, dignity, or dominion, to another; great earthquakes, and the shaking of heaven and earth, for the shaking of kingdoms, so as to distract or overthrow them; the creating a new heaven and earth, and the passing away of an old one, or the beginning and end of the world, for the rise and ruin of the body politic signified thereby.