He [the Holy Spirit] does not come when you wish, but when He does come, receive Him. But how does He come? Baptism is holy. Who makes it holy? The Holy Spirit and the blood of Christ. For Baptism did not spring from my own heart, but was established from heaven, and the Holy Spirit sanctified this Baptism. Thus I find the Holy Spirit in Baptism. Again, I find Him in the holy Supper. For you receive not mere bread and wine but the flesh and blood of Christ. I do not seek the Holy Spirit, but He seeks me. The Supper is a holy thing, and is holy, and by it the Holy Spirit makes people holy. In the same way, the Keys also are holy, when with the laying of of hands someone is made holy, not by human power but by the power of the Holy Spirit who instituted the Keys. Again, the preaching of the Gospel is not a human invention, for the Word o God was there before we were born. Thus wherever the Gospel is preached, the Holy Spirit comes and the Word sanctifies the Church. Again, if you do the Ten Commandments and attend to your vocation, God has ordered the estates and will be in them, and there also is the Holy Spirit.
Thus the Holy Spirit does not come to us by our own designs by has sufficiently appointed means by which He comes. For you have the Word, Baptism, the Supper, the Keys, the Ten Commandments; these are things of the Holy Spirit and not the worthless inventions of men. And whatever is outside of these articles the Holy Spirit has not established, and we use them only as it were swaddling cloths or a baptismal gown, which sanctify no one.
Martin Luther, First Sermon on Holy Baptism, on the Feast of Epiphany, January 6, 1539
Benjamin T. G. Mayes editor Martin Luther on Holy Baptism: Sermons to the People (1525-39) 103-104