Laudator Temporis Acti

John Hill Burton, Life and Correspondence of David Hume, Vol. II (Edinburgh: William Tait, 1846), p. 368 (letter to Hugh Blair and others, April 6, 1765):

There is a very remarkable difference between London and Paris; of which I gave warning to Helvétius, when he went over lately to England, and of which he told me, on his return, he was fully sensible. If a man have the misfortune, in the former place, to attach himself to letters, even if he succeeds, I know not with whom he is to live, nor how he is to pass his time in a suitable society. The little company there that is worth conversing with, are cold and unsociable; or are warmed only by faction and cabal; so that a man who plays no part in public affairs becomes altogether insignificant; and, if he is not rich, he becomes even contemptible. Hence that nation are relapsing fast into the deepest stupidity and ignorance. But, in Paris, a man that distinguishes himself in letters, meets immediately with regard and attention.

Hume actually wrote (emphasis added):

Hence that Nation are relapsing fast into the deepest Stupidity, Christianity & Ignorance.

See The Letters of David Hume, ed. J.Y.T. Greig, Vol. I: 1727-1765 (1932; rpt. Oxford: Oxford University Press, 2011), p. 498.