[Michael.SF.]

Guisot (also spelled as: Guizot) appears to be correct. Here is a link to an excellent explanation, which has other links to confirm this:

“Not to be a republican at twenty is proof of want of heart; to be one at thirty is proof of want of head.”

In the above link it is also stated that variations on this quotation were later attributed to Disraeli, Shaw, Churchill, and Bertrand Russell.

[wastoute]

I thought it was de Tocqueville.

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