The Man Who Counts, Chapter VII

Nicholas van Rijn, faking a poor grasp of the local language, tells a defamatory lie that initiates a fight among the Drak'honai merely so that, in the confusion, he can release their Lannachska prisoner who will, by prearrangement with van Rijn, return with an army to rescue van Rijn and his companions. Is this getting a bit too complicated to be credible? By similar deceptions, Dominic Flandry later escapes from more than one planet.

There is another, minor, parallel. When Flandry is on Talwin, a native shakes her head in disbelief. When van Rijn reminds the released prisoner to bring an army, the latter nods. I understand, although it seems hard to believe, that head-shaking for no and nodding for yes are not even universal gestures in Europe - they can be the other way around - so they should not be projected across the galaxy! We should not even assume that aliens have heads.

 However, since Poul Anderson's History of Technic Civilization assumes:

"...a universe that produces sophonts as casually as it produces snowflakes..."
-Poul Anderson, Captain Flandry: Defender Of The Terran Empire (New York, 2010), 

- there will be some who not only have heads but who also shake or nod them as we do. These seem like obvious signals to precede or supplement language or its equivalent.

In our universe, if thinking beings were as casually produced as snowflakes, then I would expect us to have found some evidence of their existence by now. Surely astronomers should be able detect obviously artificial energy sources elsewhere in the parts of space observable by optical and radio telescopes? So far, the evidence remains compatible with humanity being the only industrial-technological species in this part of the galaxy.