Could not Voltaire go and try?
It is thought Fleury had let fall some hint to that effect, carried by a bird of the air.

Sure enough Voltaire does go; is actually on visit to his royal Friend; "six days with him at Reinsberg;" perhaps near a fortnight in all (20 November-2 December or so), hanging about those Berlin regions, on the survey.

Here is an unexpected pleasure to the parties;--but in regard to penetrating of secrets, an unproductive one! Voltaire's ostensible errand was, To report progress about the ANTI-MACHIAVEL, the Van Duren nonsense; and, at any rate, to settle the Money-accounts on these and other scores; and to discourse Philosophies, for a day or two, with the First of Men.

The real errand, it is pretty clear, was as above.

Voltaire has always a wistful eye towards political employment, and would fain make himself useful in high quarters.