One Man Bucket said:
Am I the only one who thinks Vetinari is grooming Lipwig to be the next Patrician
Yes, I actually suggested this awhile ago and was generally disagreed upon but I do think that's his goal.
Vetinari understands that the "old ways" are going by the wayside. The Ankh Morpork of the future is going to have to abandon its reliance on guidds, which tend to stifle creativity and innovation, and embrance entrepreneurs with new ideas as the wave of the future. And future Patricians are going to have to rely less on keeping the guilds and aristocracy in line and more on keeping the economy of AM growing.
Vetinari understands that the "sword with the blood of a thousand men" style of leadership is out of date in this new world, and that while he can't fully escape from the traditional model, he can pave the way toward future models that make sure that AM doesn't return to the bloody Lord Snapcase models.
Moist represents the kind of future Patrician that Vetinari has in mind. The trials he subjects Moist to are tests to see how Moist handles opposition. That Moist does it through slight of hand doesn't bother Vetinari all that much--to him, the end that he wants to see justifies whatever means Moist does to achieve it.
Moist doesn't need to cowtow to the aristocracy--the dying old money of the city who are rapidly becoming obselete--because he can win the hearts of the growing middle class in AM--the craftsmen, businessmen, technologies, and Dibblers of the world who will move the city forward. Vetinari wants to create economic competition to free the city from the old ways, or at least to provide competition with monopolies (a la the post office competing with the clacks) and try to provide modern economic methods (using paper money) and shedding outdated mythologies (the importance of relying on gold).
Moist can accomplish these things. What he lacks--and what Vetinari still sees he lacks--is that violent nature that a Patrician needs to have. This is why he will continue to put Moist in challenging and potentially lethal situations--such as becoming the new tax collector. Like a master guiding the future of an apprentice, he is constantly testing Moist, with the ultimate goal being 'anointing' Moist as his successor.
J-I-B
Moist represents these ideals and represents a different style of leadership.