When our vices desert us, we flatter ourselves that we are deserting our vices.

[Quand les vices nous quittent, nous nous flattons de la créance que c’est nous qui les quittons.]

François VI, duc de La Rochefoucauld (1613-1680) French epigrammatist, memoirist, noble

Réflexions ou sentences et maximes morales [Reflections; or Sentences and Moral Maxims], ¶192 (1665-1678) [tr. Kronenberger (1959)]
    (Source)

Present in the 1st (1665) edition. In that version and the manuscript, the latter part read "... nous voulons nous flatter que c’est nous qui les quittons."

(Source (French)). Other translations:

When our Vices forsake us, we please our selves with an Opinion, that we parted first, and left them.
[tr. Stanhope (1694), ¶193]

When our vices have left us, we flatter ourselves that we have left them.
[pub. Donaldson (1783), ¶440]

When our Vices have left us, we flatter ourselves that we have left them.
[ed. Lepoittevin-Lacroix (1797), ¶184]

When our vices leave us, we flatter ourselves that we have left them.
[ed. Carvill (1835), ¶367]

When our vices quit us we flatter ourselves with the belief that it is we who quit them.
[ed. Gowens (1851), ¶201]

When our vices leave us we flatter ourselves with the idea we have left them.
[tr. Bund/Friswell (1871), ¶192]

We flatter ourselves that we quit our vices; in reality our vices quit us.
[tr. Heard (1917), ¶197]

When our vices abandon us, we flatter ourselves that it is we who abandon them.
[tr. Stevens (1939), ¶192]

When our vices depart from us, we flatter ourselves that it is we who have gotten rid of them.
[tr. FitzGibbon (1957), ¶192]

When the vices give us up we flatter ourselves that we are giving up them.
[tr. Tancock (1959), ¶192]

When our vices leave us, we flatter ourselves with the belief that it is we who have left them.
[tr. Whichello (2016) ¶192]