That always seems to be the case. 
Something for when you get back. Let me know what you think.
The concept of entropy, in particular, is central to thermodynamics. Entropy tends to be confusing because it does not have an intuitive connection to mechanical quantities, such as velocity and position, and because it is not conserved, like energy. Entropy is also frequently described using qualitative metrics such as “disorder” that are imprecise and difficult to interpret in practice. Not only do such descriptions do a terrible disservice to the elegant mathematics of thermodynamics, but also the notion of entropy as “disorder” is sometimes outright wrong. …
In reality, entropy is not terribly complicated. It is simply a mathematical function that emerges naturally for equilibrium in isolated systems, that is, systems that cannot exchange energy or particles with their surroundings and that are at fixed volume. For a single-component system, that function is
S = S(E, V, N)
which states that entropy is dependent on three macroscopic quantities: the total internal energy of the system E, the total volume of the system V, and the number of particles (molecules or atoms) N.
- M. Scott Shell. Thermodynamics and Statistical Mechanics. Chapter 2. Equilibrium and Entropy. p. 8
What does it mean to say that entropy is dependent on macroscopic quantities?
Why doesn’t the Boltzmann equation you mentioned reference these macroscopic quantities?
What does it mean to say that entropy is a state function?