"The universe is too big. This tiny segment of the fringe of one spiral arm of a single galaxy which we have somewhat explored and exploited...is too big. In going to thousands of suns that intrigue us, we have passed by literally millions of others. It will take centuries even to visit them, let alone begin to understand them a little. And meanwhile, and forever, beyond the outermost radius of our faring will lie nearly all the suns that exist." (David Falkayn: Star Trader, p. 348)
(i) Certain phraseology recurs rather often. In A Circus Of Hells, Rax says:
"'So many, many stars...a hundred billion in this one lost lonely dust-mote of a galaxy...and we on the edge, remote in a spiral arm where they thin toward emptiness...what do we know, what can we master?'" (Young Flandry, p. 217)
(ii) The trade pioneer crew explores not "...beyond the outermost radius..." but among the millions of stars already passed.
(iii) Regarding "...the outermost radius...," if reality is an infinite plane, then human knowledge is a growing but finite circle somewhere on the plane. As a circle grows, its area, the number of things known, increases but so does its circumference, the point of contact with the unknown. Thus, the more we know, the more we realize how little we know. There is an appropriate verse in a Kurt Vonnegut novel but, by searching the blog, I find that I have quoted it three times already. See here.