The first obstacle is original sin and mortal sin: the cure is God’s reviving grace.
The second is the blinding veil of our emotions, for which the cure is the intellectual vision of God’s goodness.
Third obstacle is the illusion that the things of this earth is all that is important: to counter this we must remember the transitory nature of this life in which we are just sojourners, and store up our treasure in heaven.
The fourth barrier is our own imperfection: we may have good intentions, but that is not enough to make us act out of love alone, as the perfect do. We should pray then, that we may truly desire and love the law in all its shining glory.
The fifth barrier is pride, which makes us refuse to submit to God’s commandments.
Worse, pride turns us into God’s enemies, and all too often makes those enemies attempt to tear down those who are seeking to do the good.
But, we are counseled, this must not prevent us testifying with our actions and words.
17 Retribue servo tuo, vivifica me, et custodiam sermones tuos.
18 Revela oculos meos, et considerabo mirabilia de lege tua.
19 Incola ego sum in terra : non abscondas a me mandata tua.
20 Concupivit anima mea desiderare justificationes tuas in omni tempore.
21 Increpasti superbos; maledicti qui declinant a mandatis tuis.
22 Aufer a me opprobrium et contemptum, quia testimonia tua exquisivi.
23 Etenim sederunt principes, et adversum me loquebantur; servus autem tuus exercebatur in justificationibus tuis.
24 Nam et testimonia tua meditatio mea est, et consilium meum justificationes tuæ.
17 Give bountifully to your servant, enliven me: and I shall keep your words.
18 Open my eyes: and I will consider the wondrous things of your law.
19 I am a sojourner on the earth: hide not your commandments from me.
20 My soul has coveted to long for your justifications, at all times.
21 You have rebuked the proud: they are cursed who decline from your commandments.
22 Remove from me reproach and contempt: because I have sought after your testimonies.
23 For princes sat, and spoke against me: but your servant was employed in your justifications.
24 For your testimonies are my meditation: and your justifications my counsel.
The Communio below is used on September's Ember Friday in the Extraordinary Form.
As usual, you can find an extended version of this commentary, including some aids to understanding the Latin, over at Psallam Domino.