|The thermodynamics work of Willard Gibbs have been said, e.g. by Wilhelm Ostwald (1892), Pierre Duhem (c.1905), Carlo Cercignani (1989), and Ingo Muller (2007), to contain "hidden treasures" of the the "greatest variety and importance", as Ostwald put it.|
The “hidden treasures” view of thermodynamics is a view held, albeit indirectly, by many thermodynamicists, such as Max Planck, who uncovered the hidden treasure of quantum mechanics buried or rather derived from and built on thermodynamics, to Albert Einstein, who found treasures such as the mass-energy equivalence relation as well as relativity, all stemming from his early work in thermodynamics, or Gilbert Lewis, whose work in thermodynamics and school of thermodynamics has, in the words of South African physical chemist Adriaan de Lange, “resulted in mentoring more Nobel Prize winners in chemistry than any Nobel Prize winner in any category.” 
The first person to actual come right out and say that they actually believe there to be hidden treasures in thermodynamics and that this is the sole reason for their purpose in their work was German physical chemist Wilhelm Ostwald. In 1891, Ostwald did the first translation of Gibbs’ Equilibrium into German; the second translation was done by French by French chemist Henry Le Chatelier into French in 1899.
In the preface to his 1892 Thermodynamic Studies of J. Willard Gibbs, Ostwald stated: 
“The material of the work is still of direct importance at the moment, and the interest in it is not historical. For only a small part of the almost immeasurable results which are contained and suggested here have as yet been realized. There are still hidden treasures of the greatest variety and importance here for the theoretical and most of all for the experimental worker.”
In other words, Ostwald believed that there were hidden treasures buried in Gibbs' precisely numbered 700-equations. One of the treasures Ostwald found was the science of "physical chemistry", which, working together with Dutch chemist Jacobus van't Hoff, he founded.
At the turn of the 19th century, French thermodynamicist Pierre Duhem, likewise, commented: 
"Johannes van der Waals was the first to see its hidden power, to perceive the phase rule, among the algebraic formulas where Gibbs had to some extent hidden it.”
In 1989, thermodynamics historian Carlo Cercignani commented how: 
|A 2011 Amazon.com listing (by Elliots Books, Northford, Connecticut) of the original "galley proof" of American engineer Willard Gibbs' 1876 On the Equilibrium of Heterogeneous Substances, selling for $50,000 dollars, the original copy Gibbs had to approve before the finial version was sent off to the printers.  The actuality of the selling price was verified by Libb Thims who contacted the seller.|
“Gibbs succinct and abstract style and unwillingness to include examples and applications to particular experimental situations made his work very difficult to read. Famous scientists such as Helmholtz and Planck developed their own thermodynamic methods in an independent fashion and remained quite unaware of the treasures buried in the third volume of Transactions of the Connecticut Academy of Arts and Sciences.”
Likewise, in 2007, German thermodynamics historian Ingo Muller comments on this further: 
“Ostwald, the German translator of Gibbs, had said that he undertook the task because he believed in hidden treasures in Gibbs’ work. He was right, and le Chatelier and later Haber and Bergius were chemists who uncovered and lifted the treasures as did Roozeboom.”
The fruition of some of these treasures coming to bear is evidenced in the 1949 summary that "the work of Ostwald, of Haber, of [Carl] Bosch and [Friedrich] Bergius, each of whom received a Nobel prize, was based directly on the application of Gibbs' concepts; indeed, the very first Nobel prize in chemistry went to a follower (van't Hoff). 
The following are related quotes:
“How much of the work of Gibbs is still untapped—relations that may be of chemical and biochemical importance—we cannot tell. It is interesting to remember that Gibbs had formulated the principle of Donnan equilibrium in 1876 thirty five years before Donnan. Nobody recognized this until G.S. Adair one of the few biochemists who had actually read Gibbs, pointed it out in 1923. One wonders what other precious nuggets may still be hidden in this work.”— John Edsall (1974), “Some Notes and Queries on the Development of Bioenergetics” (pg. 104)
1. De Lange, A.M. (1998). “Entropy”, Oct 30, Learning-org.com.
2. (a) Ostwald, Wilhelm. (1992). Thermodynamische Studien, von J. Willard Gibbs (preface, pg. #). Publisher.
(b) Rukeyser, Muriel. (1942). Willard Gibbs - American Genius (pg. 314). Garden City, New York: Doubleday, Doran & Co., Inc.
3. Caldi, D. G. and Mostow, George D. (1990). Proceedings of the Gibbs Symposium, May 15-17, 1989 (hidden treasures, pg. 10; section: Gibbs in economics, by Paul Samuelson, pgs. 255-68). American Mathematical Society.
4. Cercignani, Carlo. (1998). Ludwig Boltzmann - the Man Who Trusted Atoms (hidden treasures, pg. 139). Oxford: Oxford University Press.
5. Müller, Ingo. (2007). A History of Thermodynamics: the Doctrine of Energy and Entropy (pg. 128). New York: Springer.
6. Author. (1949). “Article” (pg. 15). Scientific American, 255.