I do not believe that there is a more ugly and dangerous sin than envy because it is hidden and is often covered by the attractive mantle of virtue or of friendship. Let us go further and compare it to a lion which we thought was muzzled, to a serpent covered by a handful of leaves which will bite us without our noticing it. Envy is a public plague which spares no one. We are leading ourselves to Hell without realizing it.
(from the Book “The Sermons of The Cure of Ars”, TAN Books 2013, Page 46)