And I John saw these things, and heard them; literally, and I John [am] the [one] hearing and seeing these things. The absence of the verb (the present participle being used alone) indicates the person to whom the revelation is made, without assigning any specific period as the particular time when the revelation took place.
The same statement is made in Revelation 1:1 (which see). "These things" are all that have been related in the book. And when I had heard and seen, I fell down to worship before the feet of the angel which showed me these things; and when I heard and saw, etc.
The tense here becomes aorist (vide supra). St. John has once before fallen into the same error, viz. that of paying undue homage to the angel (see on Revelation 19:10). The beatific vision overwhelms him with awe, and he is bowed down with his own humility.