John 16:12

I have yet many things to say unto you, but ye cannot bear them now.

This verse is not a separation between the fourth and fifth Paraclete sayings, but a connective making them, in fact, one saying, the first part dealing with the Spirit's relation to the world, the latter with the Spirit's work in the apostles. The need of the apostles that something should be done for them is what this verse states. There were many things the apostles could not understand until afterward. As Barnes said:

There were many things which might be said. Jesus had given them the outline, but he had not gone into details. These were things which they could not then bear.[12]

The apostles were still full of Jewish traditions; and such ideas as the total replacement of Judaism by Christianity, the cessation of the sacrifices, and the elimination of circumcision and the office of the high priest these were some of the things they could not have understood at the moment, although Jesus had indeed told them all things. Their true enlightenment would come under the guidance of the Holy Spirit.