Discourtesy is not one specific vice of the soul but the result of several vices: foolish vanity, ignorance of one’s duties, laziness, stupidity, thoughtlessness, contempt for others, and jealousy.

[L’incivilité n’est pas un vice de l’âme, elle est l’effet de plusieurs vices: de la sotte vanité, de l’ignorance de ses devoirs, de la paresse, de la stupidité, de la distraction, du mépris des autres, de la jalousie.]

Jean de La Bruyère (1645-1696) French essayist, moralist

The Characters [Les Caractères], ch. 11 “Of Mankind [De l’Homme],” § 8 (11.8) (1688) [tr. Stewart (1970)]
    (Source)

(Source (French)). Alternate translations:

Incivility is not a Vice of the Soul, but the effect of several Vices; of Vanity, Ignorance of Duty, Laziness, Stupidity, Distraction, Contempt of others and Jealousie.
[Bullord ed. (1696); Curll ed. (1713); Browne ed. (1752)]

Impoliteness is not a vice of the mind, but the consequence of several vices; of foolish vanity, of ignorance of one’s duties, of idleness, of stupidity, of absence of mind, of contempt for others, and of jealousy.
[tr. Van Laun (1885)]