Through unconnected coincidence I watched Derek Jacobi for the first time last week in two productions and in both roles he has a stammer.
I wrote about the I Claudius as I watched it but Derek Jacobi's second role as Alan Turing explaining Gödel's incompleteness theorem is masterful. The explanation is more important (logically) than Einstein's E=MC2 but its beauty is also its elegance.
Well worth listening to a few times because it dethrones mathematics and thus measurement. Goodbye empiricism.