Which is why the Churchill quote has it backwards.
Socialism is, or ought to be, an intellectually satisfying and elegant proposition to a young person. As the actually existing world of capitalism, and the deformations it induces in all of us, makes itself felt, socialism, the intellectual construct, comes to seem less feasible, and those who return the impulse monkey around with it to come up with some version of a feasible socialism.
Thus, the quote should be: if you are a young man and you aren't a socialist, then you don't have a head/brain, but if you aren't one when you are old, then you don't have a heart. The heart has been turned to stone by the filth of capitalism.
Which perhaps is one way to read Gramsci's pessimism of the intellect, changing the optimism of the will to optimism of the heart. How else could one carry on living?
kj