# Reference request on Gentzen's proof of the consistency of PA

I've always been interested in having a good understanding of Gentzen's proof of the consistency of arithmetic.

Being more precise, he showed that $$PRA + WF(\epsilon_0) \vdash Con(PA)$$.

I am interested in an exposition of his work that

1) Is transparent on which parts of the consistency proof uses the well-foundness of $$\epsilon_0$$.

2) Discuss (in mathematical and philosphical way) to what extent this proof deviate from the original Hilbert's Program, and in what extent it fits in a nice way to a more flexible formulation of this programme.