Python book for Dad?

[Rob Seastrom]

Heya folks,

My father (retired PhD metallurgist) has expressed an interest in a
"gentle introduction to Python" sort of book.

He's not a hardcore programmer, and what programming experience he has
is mostly confined to FORTRAN (probably II and IV, not even 77) so
positional significance will not be entirely foreign to him, but he's
coming at this as a smart guy with little exposure to modern
languages.

I wasn't able to get him to share with me what he expects to do with
this, but given sufficient time and motivation things like a Raspberry
Pi talking MIDI to the organ at church (the organ at home is a
first-generation Allen computer organ and predates MIDI), process
control thermometers for making jam, or other exploits are not out of
the question.

I won't reject books that are targeted at kids out of hand, but
considering the audience he may find stuff with a more advanced scope
of problems than one would give to junior high school students more
engaging.

Computer at home is a Mac, so Python 2.7 (or maybe 2.6 on his) comes
pre-installed.

Anyone got some thoughts on good books to point him at?  Dead Tree
Edition is preferred to online stuff.

-r