We have some idea, perhaps, what prayer is, but what is meditation? Well we may ask; for meditation is a lost art today, and Christian people suffer grievously from their ignorance of the practice. Meditation is the activity of calling to mind, and thinking over, and dwelling on, and applying to oneself, the various things that one knows about the works and ways and purposes and promises of God. It is an activity of holy thought, consciously performed in the presence of God, under the eye of God, by the help of God, as a means of communion with God. Its purpose is to clear one's mental and spiritual vision of God, and to let His truth make its full and proper impact on one's mind and heart. It is a matter of talking to oneself about God and oneself; it is, indeed, often a matter of arguing with oneself, reasoning oneself out of moods of doubt and unbelief into a clear apprehension of God's power and grace. Its effect is to humble us, as we contemplate God's greatness and glory, and our own littleness and sinfulness, and to encourage and reassure us - 'comfort' us in the old, strong, Bible sense of the word - as we contemplate the unsearchable riches of divine mercy displayed in the Lord Jesus Christ.
- J.I. Packer, Knowing God