From Selected Stories of Philip K Dick:

The majority of these stories were written when my life was simpler and made sense. I could tell the difference between the real world and the world I wrote about. The stories in this collection are attempts at reception–at listening to voices from another place, very far off, sounds quite faint but important. They only come late at night, when the background din and gabble of our world have faded out. Then, faintly, I hear voices from another star. Of course, I don’t usually tell people this when they ask, ‘Say, where do you get your ideas?’ I just say I don’t know. It’s safer.