This is the title of a science fiction
novel by Larry Niven
and Jerry Pournelle
. The phrase also refers to a third arm owned by Moties
, a species of aliens found in this novel. In the same series of two is to be found The mote in God's eye
From this novel originated the phrase on the gripping hand.
This novel is set in the far future, when human beings have colonized many planets. The human empire discovers an alien species which does not have interstellar travel, but which in some ways is even more advanced than we are. There is something very strange about this species. They offer both great opportunity to the human empire and great danger.
This book is a great deal of fun to real, and also reminds us of how ALIEN aliens might be - even if they don't seem it at first.