"All those industries that are based upon travel and tourism will shrink or, in some cases, disappear altogether as people are unable to go abroad like that."
Visitors to Earth
"You must see that those who are flying around in your skies are not tourists. They are not here on a science project. They are not part of some university project from some other world. They are resource explorers."
"Do not think there is a lot of tourism in the Greater Community. Perhaps between trading nations there may be. It is the problem of biological hazards. You may travel to another world to visit a museum or some kind of natural feature of that world, but because you are not of that world, there is always the problem of biological contamination. And this problem has not been universally solved." 
"Do not, then, look at the Greater Community as a vast resource awaiting your exploration. Do not think that it is a big playground where you can go and enjoy recreation, traveling around as a tourist, having adventures and so forth. These motivations all demonstrate that you do not take your life seriously and do not recognize the greater opportunity your life is giving you to discover your deeper inclinations and to find a greater fulfillment here."