The book really helped me sort out a lot of things and helped me understand the difference between trying to find life through our works (either 'positive' religious activities or 'negative' sinful fulfilment), and the realization that Christ is our true source life.
He also alludes to how we try to rely on other people as our source of life. We place great demands on our spouse, kids, and others and expect them to give us what only Christ can fulfill.
A true classic for getting away from the performance treadmill and learning the sufficiency and completeness of accepting Christ. I really ought to read it again.
Please get this book. I also recommend Dudley Hall's "Grace Works".