Their testimony foreshadowed future events.
[15]History, when written, is a recorded statement of facts and events, arranged in a chronological order.
[16]Prophecy, which is true, is a statement of facts and events foretold to take place at some future time.

Otherwise stated, prophecy is history written before it transpires.
[17]No human mind could actually foretell facts or events to happen in the future.

Only the divine mind could do that.

If, then, we find that the Bible foretold certain facts and events to happen and the record of the same was made centuries before these facts and events did happen, and these events and facts are now definitely established as having taken place, such would be the strongest proof that the persons recording such facts and events were directed in so doing by the divine mind; hence that such writing was under divine inspiration.
[18]As an illustration of this point: Wireless telegraphy and airships are modern discoveries; yet since they have been discovered we find that God, through his holy prophets, foretold centuries ago the use of such inventions.

(Job 38:35; Isaiah 60:8) The railway train has been in use less than a hundred years; and yet the prophet of God many centuries ago gave a clear and particular description of the railway train and the manner of its operation, and prophesied that the same would be in vogue at the time of the end, at the time the Lord is making preparation for the establishment of his kingdom.