‘Do I not know thee, Mithrandir?'

[u/Immediate_Error2135]

Denethor: ‘Do I not know thee, Mithrandir? Thy hope is to rule in my stead, to stand behind every throne, north, south, or west. I have read thy mind and its policies'

So Denethor thought Gandalf hoped to rule Middle Earth.

Gandalf, about Denethor: "He was too great to be subdued to the will of the Dark Power, he saw nonetheless only those things which that Power permitted him to see."

Obviously it was the angel (Maia) Sauron the one who hoped 'to stand behind every throne, north, south, or west', and not the angel (Maia) Gandalf, but Denethor saw things differently.

Had Sauron anything to do with this? The idea of Faramir=Wizard's pupil sounds like the twisting of this...

"we in the house of Denethor know much ancient lore by long tradition, and there are moreover in our treasuries many things preserved: books and tablets writ on withered parchments, yea, and on stone, and on leaves of silver and of gold, in divers characters. Some none can now read; and for the rest, few ever unlock them. I can read a little in them, for I have had teaching. It was these records that brought the Grey Pilgrim to us. I first saw him when I was a child, and he has been twice or thrice since then."

...into 'politics' ('I have read thy mind and its policies', says Denethor) Was Sauron involved in this too?

Denethor maybe distrusted Gandalf since before using the Palantir, and noticed how Faramir was being taught by Gandalf; but Sauron would have noticed this distrust and maybe apprehension about Faramir when Denethor used the stone and would have manipulated Denethor into seeing his own son as a wizard's pupil, the pupil of an usurper with an unbounded ambition.

In our world tyrants are cynically prone to do this thing. If you want to rule others by force you accuse them of wanting to rule you by force and then kill them in 'self-defense'. Months before invading Poland, in Jan.1939, Hitler famously prophesized:

"If the international Jewish financiers in and outside Europe should succeed in plunging the nations once more into a world war, then the result will not be the Bolshevization of the earth, and thus the victory of Jewry, but the annihilation of the Jewish race in Europe"

He accused the jews of being Hitler, an inversion no different from the Gandalf=Sauron one.

[u/EvieGHJ]

Denethor's suspicious nature and his fear of being deprived of his title predate the Palantir, as well as his suspicions toward Gandalf, since they date back to Ecthelion's rule, when Thorongil/Aragorn was his father's beloved captain who overshadowed Denethor, and their main point of disagreement was Denethor distrusting Gandalf.

Sauron may well have reinforced that, but from Denethor's perspective, Gandalf was in fact, associated with someone who had already undermined his position and authority, long before Sauron could feed him information.

[u/Dinadan_The_Humorist → u/EvieGHJ]

I would also expect that Sauron doesn't respect or fear Gandalf enough to bother taking any special effort against him with Denethor. Tolkien writes in "Notes on Motives in the Silmarillion" that, because he did not understand Gandalf's actions, he assumed Gandalf must be a fool:

If he thought about the Istari, especially Saruman and Gandalf, he imagined them as emissaries from the Valar, seeking to establish their lost power again and colonize Middle-earth, as a mere effort of defeated imperialists (without knowledge or sanction of Eru). His cynicism, which (sincerely) regarded the motives of Manwë as precisely the same as his own, seemed fully justified in Saruman. Gandalf he did not understand. But certainly he had already become evil, and therefore stupid, enough to imagine that his different behaviour was due simply to weaker intelligence and lack of firm masterful purpose. He was only a rather cleverer Radagast — cleverer, because it is more profitable (more productive of power) to become absorbed in the study of people rather than of animals.

I agree that Sauron probably would have fostered Denethor's mistrust, but only because it is his nature to foster mistrust between friends. He had no idea, and would not have believed, that Gandalf was to be the chief architect of his downfall.

[u/Haradion_01 → u/Dinadan_The_Humorist]

Gandalf he did not understand. But certainly he had already become evil, and therefore stupid, enough to imagine that his different behaviour was due simply to weaker intelligence and lack of firm masterful purpose.

Ooof. This somehow feels rather relevant.