The beautiful figure suggested by this passage is full of simple instruction. It is as easy to receive the Holy Ghost as it is to breathe. It almost seems as if the Lord had given them the very impression of breathing, and had said, "Now, this is the way to receive the Holy Ghost."
It is not necessary for you to go to a smallpox hospital to have your lungs contaminated with impure air. It is enough for you to keep in your lungs the air you inhaled a minute ago and it will kill you. All the pure elements have been absorbed from it, and there is nothing left but carbon and other deadly gases and fluids.
Therefore, if you are to be filled with the Holy Spirit, you must first get emptied not only of your old sinful life, but of your old spiritual life. You must get a new breath every moment, or you will die. God wants you to empty out all your being into Him, and then you will take Him in, without needing to try too hard. A vacuum always gets filled, an empty pair of lungs unavoidably breathes in the pure air. If you are only in the true attitude, there will be no trouble about receiving the Holy Ghost.