The psychological observations of great writers are more useful than most of the “science” of psychologists (of all stripes). To prove that point consider the following section from David Copperfield by Dickens.

Uriah Heep is a fawning, scheming beast who has taken advantage of another’s sorrow and willingness to drink for solace. 

In this section, he explains himself. It is quite understandable when one knows that sin begets congruent sin:

‘I am not fond of professions of humility,’ I returned, ‘or professions of anything else.’ ‘There now!’ said Uriah, looking flabby and lead-coloured in the moonlight. ‘Didn’t I know it! But how little you think of the rightful umbleness of a person in my station, Master Copperfield! Father and me was both brought up at a foundation school for boys; and mother, she was likewise brought up at a public, sort of charitable, establishment. They taught us all a deal of umbleness—not much else that I know of, from morning to night. We was to be umble to this person, and umble to that; and to pull off our caps here, and to make bows there; and always to know our place, and abase ourselves before our betters. And we had such a lot of betters! Father got the monitor-medal by being umble. So did I. Father got made a sexton by being umble. He had the character, among the gentlefolks, of being such a well-behaved man, that they were determined to bring him in. “Be umble, Uriah,” says father to me, “and you’ll get on. It was what was always being dinned into you and me at school; it’s what goes down best. Be umble,” says father, “and you’ll do!” And really it ain’t done bad!’ It was the first time it had ever occurred to me, that this detestable cant of false humility might have originated out of the Heep family. I had seen the harvest, but had never thought of the seed. ‘When I was quite a young boy,’ said Uriah, ‘I got to know what umbleness did, and I took to it. I ate umble pie with an appetite. I stopped at the umble point of my learning, and says I, “Hold hard!” When you offered to teach me Latin, I knew better. “People like to be above you,” says father, “keep yourself down.” I am very umble to the present moment, Master Copperfield, but I’ve got a little power!’ And he said all this—I knew, as I saw his face in the moonlight—that I might understand he was resolved to recompense himself by using his power. I had never doubted his meanness, his craft and malice; but I fully comprehended now, for the first time, what a base, unrelenting, and revengeful spirit, must have been engendered by this early, and this long, suppression.