by Thomas Watson
The ordinary means which the Lord uses in calling us, is not by raptures and revelations—but is,
(1.) By His Word which is "the rod of his strength" (Psalm 105:2). The voice of the Word is God's call to us; therefore He is said to speak to us from heaven (Heb. 12:25). That is, in the ministry of the Word. When the Word calls from sin, it is as if we heard a voice from heaven.
(2.) By His Spirit. This is the loud call. The Word is the instrumental cause of our conversion, the Spirit is the efficient cause of our conversion. The ministers of God are only the pipes and organs; it is the Spirit blowing in them, which effectually changes the heart. "While Peter spoke, the Holy Spirit fell on all those who heard the word" (Acts 10:44). It is not the farmer's industry in ploughing and sowing, which will make the ground fruitful, without the early and latter rain. Just so, it is not the seed of the Word that will effectually convert, unless the Spirit puts forth His sweet influence, and drops as rain upon the heart. Therefore the aid of God's Spirit is to be implored, that He would put forth His powerful voice, and awaken us out of the grave of unbelief. If a man knocks at a gate of brass, it will not open; but if he comes with a key in his hand, it will open. Just so, when God, who has the key of David in His hand (Rev. 3:7) comes, He opens the heart, though it be ever so fast locked against Him.
From All Things for Good by Thomas Watson