Earthly things — i.e., things upon earth, having the sphere of their action upon earth. These are not necessarily restricted to the subjects of this interview. The context includes previous witness borne by Him, and there must have been much which is unrecorded. (Comp. John 2:23.) But the new birth is not excluded from “earthly things,” because it is the entrance to a life which, while it is spiritual, is still a life upon earth.
Heavenly things, in the same way, are things which have the sphere of their action in heaven, the full development of the spiritual life, of which the birth only is on earth; the divine counsels of redemption; the Messianic mysteries, of which this ruler of Israel does not understand even the initiation. Comp. the question in the Wisdom of Solomon, “What man is he that can know the counsel of God? or who can think what the will of the Lord is?... And hardly do we guess aright at things that are upon earth, and with labour do we find the things that are before us: but the things that are in heaven who hath searched out?” (John 9:13; John 9:16).
The earthly things are the elements of spiritual knowledge, having their test in the moral sense and in their fitness to supply the spiritual wants of man. When these elements are learnt, the mind is then, and then only, fitted to receive heavenly things. The teaching can only proceed step by step from the known to the unknown; but if the will refuses or the intellect neglects to know the knowable, the man cuts himself off from the power to receive truth. The message from the spirit-world has come, and others read it; but he has not learnt the alphabet. (Comp. Note on John 16:12.)