Our ignorance, of course, has always been with us, and always will be. What is new is our awareness of it, our awakening to its fathomless dimensions, and it is this, more than anything else, that marks the coming of age of our species. Space may have a horizon and time a stop, but the adventure of learning is endless.

Coming of Age in the Milky Way, Chapter 20 (p. 383), William Morrow & Company, Inc. 1988