Can someone check a quote from Unfinished Tales?

[Firefoot]

And this the Valar did, desiring to amend the errors of old, especially that they had attempted to guard and seclude the Eldar by their own might and glory, fully revealed; whereas now their emissaries were forbidden to reveal themselves in forms of majesty, or to seek to rule the wills of Men or Elves by open display of power, but coming in shapes weak and humble were bidden to advise and persuade Men and Elves to good, and to seek to unite in love and understanding all those whom Sauron, should he come again, would endeavour to dominate and corrupt.

Page 406, Ballantine Books DelRey. Copyright 1980 by George Allen & Unwin (Publishers) Ltd. I think it is the first edition (If UT has more than one edition) because it doesn't say anything about that.

I hope this helps!