17 ‘It will be in the last days, says God:

I will pour out from my Spirit upon all flesh;

your sons and your daughters will prophesy;

your young men will see visions;

your old men will dream a dream.*"Visions" is plural, but "dream" is singular, in the Text (albeit 15% of the Greek manuscripts do have ‘dreams’). When I was young I had all sorts of ‘visions’ of what I thought I was going to achieve in my lifetime. Now that I am old I am pretty well reduced to one ‘dream’. One’s focus must accompany his energy level. (My personal experience is probably not the intended meaning of the Text, but I am not sure what it might be—do all old men have the same dream?)

18 In those days I will indeed pour out from my Spirit upon my male slaves and upon my female slaves,

and they will prophesy.*As is typical in Hebrew, verse 18 repeats part of verse 17. Similarly, verse 20 complements verse19. I take it that verses 19 and 20 will be fulfilled during the Great Tribulation, literally, so it was verses 17 and 18 that were immediately applicable to what was happening there. So why did Peter quote the material in 19 and 20? Perhaps he (and the others) thought that ‘the day of the Lord’ had already started—so much so that no one went home; the believers stayed on in Jerusalem until the persecution sent them running (Acts 8:1).

19 I will show wonders in the heaven above

and signs on the earth below:

blood and fire and smoke vapor.

20 The sun will be turned into darkness

and the moon into ‘blood’

before the great and glorious day of the Lord will come.

21 And it will be: whoever calls on the name of the Lord*To call on the ‘name’ of the Lord is to call on Him. To ‘call’ on Him is to place yourself under His protection, which involves a recognition of His rulership.

will be saved!’