Sinister Barrier

A classic novel by Eric Frank Russell first published in Unknown in 1939.

The main character investigates the suicide of a series of famous scientists and slowly discovers that they all had treated themselves with an odd combination of chemicals, and that something they saw after the treatment drove them to insanity or suicide. He treats himself, and discovers that new can now see gaseous blobs — Vitons — which appear to be feeding off human emotion. Apparently intelligent, they seem to be milking humanity and controlling it to produce the maximum of emotion, causing wars and other evils.

He starts spreading the word and is immediately chased by the Vitons. As more and more people become aware of them, the Vitons switch from herding to extermination, and in an all-out war, humanity is — barely — the victor.

Sinister Barrier is a novel based on Charles Fort's idea that "men are cattle" of seem unknown advanced race. See also Forteanism. It had a fairly significant impact on fans and more than anything bought Fort's ideas into the mainstream (of sf anyway) as a fertile source of ideas.