These statements were, as he felt even in making them, not only gratuitous, but utterly unconvincing, but he had arrived at that condition in which a man discovers with terror the unsuspected amount of mendacity latent in his system.

F. Anstey (1856-1934) English novelist and journalist (pseud. of Thomas Anstey Guthrie)

The Brass Bottle, ch. 9 “Persicos Odi, Puer, Apparatus” (1900)
    (Source)

Originally published in The Strand Magazine (1900-04).