In the Author Commentary to the reprint of the paper paper *[Diagonal Arguments and Cartesian Closed Categories](http://www.tac.mta.ca/tac/reprints/articles/15/tr15abs.html)* in *Theory and Applications of Categories* Bill Lawvere wrote:



> 
> Although the cartesian-closed view of function spaces and functionals was intuitively obvious in all but name to Volterra and Hurewicz (and implicitly to Bernoulli), it has counterexamples within the rigid framework advocated by Dieudonné and others. According to that framework the only acceptable fundamental structure for expressing the cohesiveness of space is a contravariant algebra of open sets or possibly of functions. Even though such algebras are of course extremely important invariants, their nature is better seen as a consequence of the covariant geometry of figures. Specific cases of this determining role of figures were obvious in the work of Kan and in the popularizations of Hurewicz’s k-spaces by Kelley, Brown, Spanier, and Steenrod, but in the present paper I made this role a matter of principle: the Yoneda embedding was shown to preserve cartesian closure, and naturality of functionals was shown to be equivalent to Bernoulli’s
> principle.
> 
> 
> 


First of all, as if I understand correctly the mention of Bernoulli refers to [Johann Bernoulli](https://en.wikipedia.org/wiki/Johann_Bernoulli) (1667 – 1748) which is known for his contributions to infinitesimal calculus and educating Leonhard Euler in the pupil's youth. Am I correct thinking so?


Secondly, which principle exactly does the author mention in the passage? The only Bernulli principle which comes on my mind is [Daniel Bernoulli's principle](https://en.wikipedia.org/wiki/Bernoulli%27s_principle) in fluid dynamics.



Mention of Bernoulli principle by Bill Lawvere
Since the topic of Lawvere paper is differential geometry, the Bernoulli is likely [Jacob Bernoulli,](https://en.wikipedia.org/wiki/Jacob_Bernoulli) or his brother [Johann,](https://en.wikipedia.org/wiki/Johann_Bernoulli) and refers to their calculus of variations and the principle of virtual work. Further evidence is this [paper](http://denise.vella.chemla.free.fr/Lawvere-categ-3.pdf) by Lawvere on category theory, where he explicitly refers to Bernoulli in the context of the calculus of variations.


