The meaning of this verse seems to be that when Moses went into the Holy Place to speak with God he became conscious of the Divine voice, that opened out to him the thoughts and purposes of God in such a way that he was caught up on the current and borne back to God.
This is the true conception of prayer. We often go to God with our thoughts and desires, and having uttered them we go our way. We do not wait long enough to see the cherubim and the light of the Shekinah, or hear the Divine voice. Thus our prayers fail of their answer. We do not ask what is according to the will and mind of our Heavenly Father; and the heavens seem like brass. We have not because we ask not, or because we ask amiss. We must ask in faith, nothing wavering.
The true conception of prayer is that it originates in the purpose of God, and passes from the Father to the Son, who is also the Head and Representative of His people. From Jesus it is brought into our hearts by the blessed Spirit, who unites the Head with each member of the mystical body; and from the saints it returns to the source from which it came.
If, then, we would pray aright, we should wait before God until the Holy Spirit suggests what we should pray for, and indeed begins to plead within us for the saints. Silence, solitude, waiting before God; the return to God of His own thoughts; the being burdened with the weighty matters that lie heavily on the heart of Jesus - such is the noblest kind of prayer. It is those who wait upon the Lord that renew their strength, that mount up with wings as eagles; that run and are not weary, that walk and are not faint (Isa 40:31).