In one of the first few chapters, Barth talks about proving the existence of God. He thinks these proofs we've constructed about the existence of God don't really do anything but prove our short-sightedness. He thinks the other way around. To him, the idea of God is more concrete than the idea of himself. The experience of life can seem like a dream; how do you know it's real? Basically, he is working from the framework that God is the solid rock of understanding and that we are like shifting sand.
It's a highly philosophical point, and one that I don't quite know that I fully understand, but the Spirit brought an "aha!" moment to me as I was reading this section of Scripture in 1 Corinthians 2:
For the Spirit searches everything, even p the depths of God. 11 For who knows a person's thoughts q except the spirit of that person, which is in him? So also no one comprehends the thoughts of God except the Spirit of God. 12 Now r we have received not s the spirit of the world, but the Spirit who is from God, that we might understand the things freely given us by God.13 And we impart this t in words not taught by human wisdom but taught by the Spirit,u interpreting spiritual truths to those who are spiritual
The realization dawned on me: knowing God is a gift! To interact with, to think about, to have a relationship with God is quite an astonishing thing when you stop to think about it. It is a precious gift to know him. It's undeserved grace. Knowing God. It helps to think of it as a gift. This isn't a relationship I control or manage. It's interactivity, it's submission and obedience, and it's joy.
I'm not sure that's what Karl Barth intended when he wrote that section of his book, but the beautiful thing about communicating the things of God is that the Spirit works to bring understanding in mysterious ways.