" I find this most useful. It justifies the expert time spent upon it. We now have a number of so-called facts each preceded by the word 'probably'. It shows commendable caution on the part of those who don't want to accept responsibility for their own statements."
"An intelligent guess is better than no guess at all, Your Excellency," suggested Shelton, who by now had worked off his ire on the unfortunate Trooper Casartelli.
"It isn't even an intelligent guess," denied the Ambassador. "It is based solely on what can be seen. No account has been taken of what cannot be seen."
"I don't know how it is possible to do that," said Shelton, failing to understand what the other was getting at.
"I neither ask nor expect the impossible," the Ambassador gave back. "My point is that data based exclusively on the visible may be made completely worthless by the invisible." He tapped the report with an authoritative forefinger. "They estimate sixteen thousand strongholds -- above ground. How many are below ground?"
"Subterranean ones?" exclaimed Shelton, startled.
"Of course. There may be fifty thousand of those for all we know."
"We didn't see any."
"He says we didn't see any," the Ambassador said to Grayder. "

― Eric Frank Russell , The Great Explosion