Revelation 1:19

ἅ εἶδες. If the Revelation be a homogeneous record of a single trance, this must mean the vision just described, otherwise we might think the Seer was bidden to write all his visions. Jeremiah had prophesied more than twenty years (Jeremiah 1:2; Jeremiah 36:1) before he was bidden to write. If so it would follow from μετὰ ταῦτα and ἡ φωνὴ ἡ πρώτη Revelation 4:1 that the earlier visions pass again before the Seer.

ἃ εἰσίν. Whether the verse means that the Seer is to write the whole vision, whether of past, present or future events, or that he is to write the vision and its interpretation and its appointed sequel, is hard to decide because there is nothing in the general arrangement of the book to support either sense. The use of εἰσὶν twice in the following verse (perhaps in Revelation 16:14), and Revelation 17:9 sqq. tells in favour of the latter, so too does the change from the plural εἰσὶν to the singular ἃ μέλλει γίνεσθαι. In a careful writer this would almost certainly mark a contrast between the several meanings of what was shown in the visions and the mass of future events.