Packer wrote the following gem about Luther's approach to doing theology:
When Martin Luther wrote the Preface to the first collected edition of his many and various writings, he went to town explaining in detail that theology, which should always be based on the Scriptures, should be done according to the pattern modelled in Psalm 119.
There, Luther declared, we see three forms of activity and experience make the theologian.
The first is prayer for light and understanding.
The second is reflective thought (meditatio), meaning sustained study of the substance, thrust, and flow of the biblical text.
The third is standing firm under pressure of various kinds (external opposition, inward conflict, and whatever else Satan can muster: pressures, that is, to abandon, suppress, recant, or otherwise decide not to live by, the truth God has shown from his Word.
Luther expounded this point as one who knew what he was talking about, and his affirmation that sustained prayer, thought, and fidelity to truth whatever the cost, became the path along which theological wisdom is found is surely one of the profoundest utterances that the Christian world has yet heard.