VERTEX: Do you use the I Ching as a plotting device in your work?
DICK: Once. I used it in The Man in the High Castle because a number of characters used it. In each case when they asked a question, I threw the coins and wrote the hexagram lines they got. That governed the direction of the book. Like in the end when Juliana Frink is deciding whether or not to tell Hawthorne Abensen that he is the target of assassins, the answer indicated that she should. Now if it had said not to tell him, I would have had her not go there. But I would not do that in any other book.
VERTEX: What is the importance of the I Ching in your own life?
DICK: Well, the I Ching gives advice beyond the particular, advice that transcends the immediate situation. The answers have an universal quality. For instance: "The mighty are humbled and the humbled are raised." If you use the I Ching long enough and continually enough, it will begin to change and shape you as a person. It will make you into a Taoist, whether or not you have ever heard the word, whether or not you want to be.
DICK: I've been using the I Ching since 1961, and this is what I use it for, to show me a way of conduct in a certain situation. Now first of all it will analyze the situation for you more accurately than you have. It may be different than what you think. Then it will give you the advice. And through these lines a torturous, complicated path emerges through which the person escapes the tragedy of matrydom and the tragedy of selling out. He finds the great sense of Taoism, the middle way. I turn to it when I have that kind of conflict.
And from an interview two years later:
Phil: I don't use the I Ching anymore. I'll tell ya, the I Ching told me more lies than anybody else I've ever known. The I Ching has a personality and it's very devious and very treacherous. And it feeds ya just what you want to hear. And it's really spaced out and burned out more people than I would care to name. Like a friend is somebody who doesn't tell you what you want to hear. A friend tells you what's true. A toady is the old word for somebody who told you what you wanted to hear. The Kings all had their toadies around them who told them what they wanted to hear. The King said, am I the greatest King in the world? Yeah, you're the greatest King in the world, yeah. Well, this is what the I Ching does. It tells you what you want to hear and it's not a true friend. One time I really zapped it. I asked it if it was the devil. And it said yes. And then I asked it if it spoke for God, and it said no. It said I am a complete liar. I mean that was the interpretation. In other words I set it up. I set it up. I asked two questions simultaneously and it said I speak with forked tongue, is what it said. And then it said, oops, I didn't mean to say that. But it had already –
 - http://www.philipkdickfans.com/literary-criticism/frank-view...
 - http://www.philipkdickfans.com/literary-criticism/interviews...
He wrote an entire book (exegesis) in which he meticulously describes his exploration of psychotic states and experiences that shook him and shattered his idea of reality. This is not what a "crazy" person does.
"He threw the grenade into the jeep" doesn't sound crazy to me when referencing the choices of an AI. The I Ching just requires a human computer to execute world ticks.
Astrology is just really old computer games about life for a really crusty computing platform.