It is possible for us, therefore to find in the Psalter not only the reflection of our own soul’s state, together with precept and example for all possible conditions, but also a fit form of words wherewith to please the Lord on each of life’s occasions, words both of repentance and of thankfulness, so that we fall not into sin; for it is not for our actions only that we must give account before the Judge, but also for our every idle word.
When you would give thanks to God at your affliction’s end, sing Psalm 4, Psalm 75 and Psalm 116. When you see the wicked wanting to ensnare you and you wish your prayer to reach God’s ears then wake up early and sing Psalm 5.
For victory over the enemy and the saving of created things, take not glory to yourself but, knowing that it is the Son of God who has thus brought things to a happy issue, say to Him Psalm 9; and when you see the boundless pride of man, and evil passing great, so that among men (so it seems) no holy thing remains, take refuge with the Lord and say Psalm 12. And if this state of things be long drawn out, be not faint-hearted, as though God had forgotten you, but call upon Him with Psalm 27.
If you want to know how Moses prayed, you have the 90th Psalm. When you have been delivered from these enemies and oppressors, then sing Psalm 18; and when you marvel at the order of creation and God’s good providence therein and at the holy precepts of the law, Psalm 19 and Psalm 24 will voice your prayer; while Psalm 20 will give you words to comfort and to pray with others in distress.
When you yourself are fed and guided by the Lord and, seeing it, rejoice, the 23rd Psalm awaits you. Do enemies surround you? Then lift up your heart to God and say Psalm 25, and you will surely see the sinners put to rout. And when you want the right way of approach to God in thankfulness, with spiritual understanding sing Psalm 29.