That first novel of mine, Non-Stop, is directly attributable to Heinlein. His "Common Sense" seemed to me such a good story, but bereft of any human feelings. I thought long about that story, and then I thought how wonderful it would be to write about a spaceship in which people have been imprisoned for generations and to put in something of the human feeling. So that novel is directly attributable to Heinlein. I thought, in my youthful arrogance, that I could do it better I didn't! I thought I could do it differently, and I think I did do it differently. And I suppose that on the whole, I've concentrated on doing things differently ever since.