We so often get caught up in the ways of the world, and lost in them, that we often need refresher courses of heavenly realities: things like how God is and how life is. So often we put human characteristics (and limitations) on God when realIy that's not true at all. Doing this type of thing hugely limits the richness of the faith because you're putting a huge limit to your understanding of God's nature.
Why is understanding God's nature important? Because you have to understand who you're communicating with, as with any relationship. So often do we treat Him in certain ways as if he's a normal, flawed human, like our other relationships. What a mistake this is! We can count and depend on Him like no other! He knows us better than no other! I've reread these writings from Liguori multiple times and every time it feels like I say to myself "Oh yeah, that's right! I forgot that!"
This is one of the most important aids you can have for your spiritual life as it will allow you to communicate more perfectly with God in a manner that is most pleasing to Him.