Table talk, lovers’ talk — both are equally elusive. Lovers’ talk is castlebuilding, table talk is pipe-dreaming.

[Propos de table et propos d’amour; les uns sont aussi insaisissables que les autres; les propos d’amour sont des nuées, les propos de table sont des fumées.]

Victor Hugo (1802-1885) French writer

Les Misérables, Part 1 “Fantine,” Book 3 “The Year 1817,” ch. 6 (1.3.6) (1862) [tr. Donougher (2013)]
    (Source)

(Source (French)). Alternate translations:

Table talk and lovers' talk equally elude the grasp; lovers' talk is clouds, table talk is smoke.
[tr. Wilbour (1862)]

Love talk and table talk are equally indescribable, for the first is cloud, the second smoke.
[tr. Wraxall (1862)]

Chat at table, the chat of love; it is as impossible to reproduce one as the other; the chat of love is a cloud; the chat at table is smoke.
[tr. Hapgood (1887)]

Table-talk and lovers’ talk, both fleeting as air. Lovers’ talk is the mist and table-talk the scent.
[tr. Denny (1976)]

Table talk and lovers' talk are equally elusive; lovers' talk is clouds, table talk is smoke.
[tr. Wilbour/Fahnestock/MacAfee (1987)]