CRY FROM A FAR PLANET By TOM GODWIN - https://www.gutenberg.org/cache/epub/23799/pg23799-images.html

 

A smile of friendship is a baring of the teeth. So is a snarl of menace. It can be fatal to mistake the latter for the former.

Harm an alien being only under circumstances of self-defense.

TRUST NO ALIEN BEING UNDER ANY CIRCUMSTANCES.