Daniel 8:1

Here is, I. The date of this vision, Dan 8:1. It was in the third year of the reign of Belshazzar, which proved to be his last year, as many reckon; so that this chapter also should be, in order of time, before the fifth. That Daniel might not be surprised at the destruction of Babylon, now at hand, God gives him a foresight of the destruction of other kingdoms hereafter, which in their day had been as potent as that of Babylon. Could we foresee the changes that shall be hereafter, when we are gone, we should the less admire, and be less affected with, the changes in our own day; for that which is done is that which shall be done, Ecc 1:9. Then it was that a vision appeared to me, even to me, Daniel. Here he solemnly attests the truth of it: it was to him, even to him, that the vision was shown; he was the eye-witness of it. And this vision puts him in mind of a former vision which appeared to him at the first, in the first year of this reign, which he makes mention of because this vision was an explication and confirmation of that, and points at many of the same events. That seems to have been a dream, a vision in his sleep; this seems to have been when he was awake. II. The scene of this vision.

— Matthew Henry's Concise Commentary (public domain)