Many explain that this stillness refers only to worldly matters; in other words, that during prayerful converse with God you must ‘be still’ with regard to worldly affairs. But I will tell you in the name of God that not only is it necessary to be dead to them at prayer, but when by the omnipotent power of faith and prayer our Lord God the Holy Spirit condescends to visit us, and comes to us in the plenitude of His unutterable goodness, we must be dead to prayer too.
The soul speaks and converses during prayer, but at the descent of the Holy Spirit we must remain in complete silence, in order to hear clearly and intelligibly all the words of eternal life which He will then deign to communicate. Complete soberness of both soul and spirit, and chaste purity of body is required at the same time. The same demands were made at Mount Horeb, when the Israelites were told not even to touch their wives for three days before the appearance of God on Mount Sinai. For our God is a fire which consumes everything unclean, and no one who is defiled in body or spirit can enter into communion with Him.
(St. Seraphim of Sarov: A Spiritual Biography by Archimandrite Lazarus Moore, Chap. 8)