Silmarillion - Chapter 01 - Of the Beginning of Days

[Raynor]

Here is the passage I had in mind:

Originally Posted by Osanwe kenta

The hroa and tengwesta have inevitably some like effect upon the Valar, if they assume bodily raiment. The hroa will to some degree dim in force and precision the sending of the thought, and if the other be also embodied the reception of it. If they have acquired the habit of tengwesta, as some may who have acquired the custom of being arrayed, then this will reduce the practice of Osanwe. But these effects are far less than in the case of the Incarnate.