See my post to the Albert Einstein Discussion Page in Wikiquote. Here's what I think the quote should be:
A theory is the more impressive the greater the simplicity of its premises is, the more different kinds of things it relates, and the more extended is its area of applicability. Therefore, the deep impression that classical thermodynamics made upon me. It is the only physical theory of universal content concerning which I am convinced that, within the framework of the applicability of its basic concepts, it will never be overthrown.
I blogged about this quote a while back. It just occurred to me that irony itself is yet another manifestation of entropy: a gap between intended meaning (macrostate) and possible meanings (microstates).