'The first resurrection,' mentioned in Revelation 20:5, 6, does not mean a first resurrection, but the essence and primary part of resurrection, which is salvation and eternal life. There is only one resurrection to life. A second does not happen, and is not mentioned anywhere in the Bible.

(References: Apocalypse Explained 6; Apocalypse Revealed 851; Revelation 20:5-6)

493. There is no need to pause too long over the consideration that 'days' and 'years mean periods of time and states. Only this need be stated here, that in the world periods of time and measurements to which numbers may be applied are indispensable, for they belong within the ultimate realms of nature. But whenever such application occurs, the numbers of days and years, and also the numbers applied to measurements, mean something which is completely different from periods of time or from measurements, and which is determined by the meaning of the number used, as in the statements about there being six days for work, and the seventh being holy, which are dealt with above; in the statement about a jubilee having to be announced every forty-ninth year and celebrated in the fiftieth; about the tribes of Israel being twelve, the same number as the Lord's Apostles; and about there being seventy elders, the same number as the Lord's disciples. And there are many other examples where the numbers mean some special characteristic completely different from the persons or objects to which they apply. And when completely separated one from the other the states meant by the numbers are then left.