"Error nearly always has its origin, not in profound and laborious studies, but in the tripleheaded monster which St. John describes and calls: 'Concupiscence of the flesh, concupiscence of the eyes, the pride of life.' Here are the sources of all error ... Very often corruption of heart is a consequence of errors of the intellect; but more frequently still errors of the intellect follow the CORRUPTION OF THE HEART. The history of heresies very clearly shows this fact. Their beginnings nearly always present the same character, either wounded self-love, or a grievance to be avenged."
Fr. Salvany, from his classic book, "Liberalism is a Sin", Page 133