As to why the government would cover up the alien presence:
1. People, being foolish, have used the alien technology for undesirable purposes. (Like the Montauk Project, for ex.) If they admit that ETs exist,
ALL that doo-doo would come out as well.
2.They might CLAIM that they can't protect us from ETs, so they deny that aliens exist. (That excuse doesn't make sense.)
3. The government probably feels VERY UNEASY to know that a LARGE segment of the population has been abducted, and therefore MAY have their
allegiance compromised.
The Motives of the Aliens:
Varied, because there are SO MANY kinds of aliens visiting Earth. Some are "good", some "bad" or neutral.
How Humans Would Respond to the Disclosure of the ETs:
VARIED! You know, the Americans would not respond just the same way as tribesmen in The Congo, for example. We humans have so much variety in
cultures that we would all respond differently. Personally, I think that MOST of us would not panic. We are now living in the Space Age, not the
1930's.
I am an abductee/contactee.


