Aerospace at Troynovant:
Winging and thrusting into Air & Space;
visionaries, scientists, & engineers
and the development of designs & vehicles;
listed by Title

Naturally the fact that so much that was theory is now reality has changed the public attitude. When I wrote about the idea of space travel in 1944 I felt it was necessary to put considerable emphasis on the fact that I was serious. Every sentence which was not strictly historical was carefully weighed; I wanted to impress upon the reader that the people who had thought about space travel were people who knew how to think. This is now generally taken for granted.

The question is no longer whether space-travel theory is serious, or whether it is correct. The question now is simply how soon engineering practice will catch up with existing theory.

Willy Ley
"Foreword"
Rockets, Missles, and Space Travel  (1951)