This Book of the Law shall not depart from your mouth, but you shall meditate on it day and night, so that you may be careful to do according to all that is written in it. For then you will make your way prosperous, and then you will have good success. (Joshua 1:8 ESV)
To me, this verse in metaphysical terms is a reference to affirmations, or meditations upon statements of truth. "This book of the law shall not depart out of my mouth" to me speaks of verbally repeating statements of truth or affirmations to embed them in our consciousness not only by thinking about them, but also hearing my own voice speak them.
Interestingly enough, there are only four places in the Bible that promise success, and every one of them contains a reference to meditation. In particular, they contain a reference to meditation upon the law of God or the word of God, that is, upon spiritual truth.
Another such reference is Psalm 1. In it, referring to a man of God, it says:
"His delight is in the law of the Lord, and in this law doth he meditate day and night. And he shall be like a tree planted by the rivers of water, that bringeth forth his fruit in his season. His leaf also shall not wither, and whatsoever he doeth shall prosper."
Notice that both of these verses refer to meditating "day and night." To me, this implies constant or near constant meditation. It means keeping the truth in our minds as much as possible all of the time. The easiest way to facilitate that is to memorize statements of truth.
In another of the verses that I see as referring to meditation, we read:
"You shall therefore lay up these words of mine in your heart and in your soul, and you shall bind them as a sign on your hand, and they shall be as frontlets between your eyes. You shall teach them to your children, talking of them when you are sitting in your house, and when you are walking by the way, and when you lie down, and when you rise. (Deuteronomy 11:18, 19 ESV)
God then goes on to promise: "Every place on which the sole of your foot treads shall be yours." In other words, you will take possession of everything that I have promised to you—another way of saying you will be successful. And all of this is predicated upon laying up the word of God in your heart, or memorizing it, and then speaking of it as you sit in your house, for instance at meals, or when you're walking from place to place, when you lie down to sleep at night, and when you first rise up in the morning.
