LotR -- Book 3 - Chapter 11 - The Palantír

[Kuruharan]

I don't recall ever reading anything that equated the light of the Trees with the Secret Fire.

I view the Trees as being a creation of the Valar, which they were able to hallow and fill with light by their own power.

I believe the Secret Fire belonged to Eru and Eru alone.

Perhaps the danger with the Palantiri is the same as with the Ring

But I don't think this was always the case. I don't think the palantiri were always dangerous.

At least, we don't have a story about some vision-hooked royal functionary being dragged away from the palantir screaming, "Just one more peep show, that's all I ask!!"