Note 8 at Joh 3:13: This verse is as some of Paul's writings that Peter said were "hard to be understood" (2Pe 3:16). Some have said that Jesus stopped speaking in Joh 3:12 and that John was again speaking in Joh 3:13 through the end of this chapter. That would certainly make this verse very easy to understand, but the context suggests that it was still Jesus speaking through Joh 3:21. It is more probable that Jesus simply gave Nicodemus a little taste of some of those heavenly mysteries that He made reference to in Joh 3:12.