The following is from a message by Thomas Watson entitled, The Christian Soldier, preached in 1669.
Meditation is a holy exercise of the mind; whereby we bring the truths of God to remembrance--and seriously ponder upon them and apply them to ourselves. It is a work which cannot be done in a crowd. A Christian must retire from the world, to have serious thinking upon God. It is not a few transient thoughts that are quickly gone;but a fixing and staying of the mind upon heavenly objects.
As the bee sucks the honey from the flower--so by meditation we suck out the sweetness of a truth. It is not the receiving of food into the mouth, but the digesting of it, which makes it nutritious. Just so, it is not the receiving of the most excellent truths in the ear, which nourishes our souls--but the digesting of them by meditation.
Satan does what he can to hinder this duty. He is an enemy of meditation. The devil does not care not how much we read--so long as we do not meditate on what we read. Reading begets knowledge--but meditation begets devotion.
Oh, how love I thy law! It is my meditation all the day. - Psalm 119:97
Holy meditation quickens the affections. The reason why our affections are so cold to heavenly things--is because we do not warm them at the fire of holy meditation. As the musing on worldly objects makes the fire of lust burn; and as the musing on injuries makes the fire of revenge burn; just so, meditating on the transcendent beauties of Christ, would make our love to Christ flame forth.
Meditation has a transforming power in it. The reading of the Word may affect us--but the meditating upon it transforms us. Meditation stamps the impression of divine truths upon our hearts. By meditating on God's holiness, we grow holy. While by meditation we look upon God's purity--we are changed into His likeness.
Meditation produces reformation.
I thought on my ways, and turned my feet unto they testimonies. - Psalm 119:59.
If we would spend but one quarter of an hour every day in contemplating heavenly objects, it would leave a mighty impression upon us!