Blessed is the man who hath not walked in the counsel of the ungodly, nor stood in the way of sinners, nor sat in the chair of pestilence. But his will is in the law of the Lord, and on his law he shall meditate day and night (Psalm 1:1-2).
The Prophet, in portraying in the likeness of God the man that is perfect—one who may serve as a noble example of eternal happiness—points to the exercise by him of no commonplace virtues, and to the words, But his will hath been in the Law of the Lord, for the attainment of perfect happiness.
To refrain from what has gone before is useless unless his mind be set on what follows, But his will hath been in the Law of the Lord. The Prophet does not look for fear.
The majority of men are kept within the bounds of Law by fear; the few are brought under the Law by will: for it is the mark of fear not to dare to omit what it is afraid of, but of perfect piety to be ready to obey commands.
This is why that man is happy whose will, not whose fear, is in the Law of God. But then sometimes the will needs supplementing; and the mere desire for perfect happiness does not win it, unless performance wait upon intention.
The Psalm, you remember, goes on: And in His Law will he meditate day and night. The man achieves the perfection of happiness by unbroken and unwearied meditation in the Law.
Now it may be objected that this is impossible owing to the conditions of human infirmity, which require time for repose, for sleep, for food: so that our bodily circumstances preclude us from the hope of attaining happiness, inasmuch as we are distracted by the interruption of our bodily needs from our meditation by day and night.
Parallel to this passage are the words of the Apostle, Pray without ceasing (1 Thess. 5:17). As though we were bound to set at naught our bodily requirements and to continue praying without any interruption!
Meditation in the Law, therefore, does not lie in reading its words, but in pious performance of its injunctions; not in a mere perusal of the books and writings, but in a practical meditation and exercise in their respective contents, and in a fulfilment of the Law by the works we do by night and day, as the Apostle says: Whether ye eat or drink, or whatsoever ye do, do all to the glory of God (1 Cor. 10:31).
The way to secure uninterrupted prayer is for every devout man to make his life one long prayer by works acceptable to God and always done to His glory: thus a life lived according to the Law by night and day will in itself become a nightly and daily meditation in the Law.
Hilary of Poitiers (c.300-368): On the Psalms, Psalm 1, 11-12.