I'm putting my bet on INFP.
Dominant- Fi (his interest in his personal development and growth and his intention to live the way he did just screams it)
Auxiliary- Ne (ISFPs would not be inspired by intellectual books from centuries past)
Tertiary- Si (Tertiary Si, I would presume, is most responsible for naturalist tendencies in INxPs)
Animus- Te "I am able to establish rules or make plans to achieve what I consider as important."