Meta. The "upper chamber" to which the disciples went for the baptism of the Holy Spirit is the high state of mind that we assume in thinking about spiritual things. It may be attained through prayer, or going into the silence with true words, or in spiritual meditation. There are various methods for making this attainment, but in order to have this Holy Spirit baptism we must be looking for it; that is, our attention must be toward things spiritual.
When the earnest Christian has such unusual experiences the thought comes into his mind, "It must be that I am coming into an abiding spiritual state of consciousness." The disciples asked, "Lord, dost thou at this time restore the kingdom to Israel ? And he said unto them, It is not for you to know times or seasons, which the Father hath set within his own authority" (Acts 1:6, 7). The Christian does not know when the final change will come, when "this corruptible shall have put on incorruption." He does find, however, that he gets the consciousness of the descent of spiritual power, which is witnessed in "the uttermost part of the earth," or his body.
After a great spiritual illumination we find our mind and heart reaching out for heavenly things until we almost forget our practical life. We continue to look steadfastly into heaven until the "two men . . . in white apparel" (consciousness of Spirit within and about us) call our attention to the fact that this new man in Christ has not left us but will return in the same manner in which he went--that is, in consciousness.