Dag, the next paragraph in Piketty:
Not until 1901 was the sacrosanct principle of proportionality in taxation
finally undone. The law of February 25, 1901, established a progressive tax on inheritances, the first progressive tax adopted in France. A progressive tax on income followed with the law of July 15, 1914. Both taxes occasioned lengthy parliamentary debates, and it was the French Senate—the more conservative of the two chambers, because rural areas and notables were overrepresented in it—that delayed adoption of the progressive inheritance tax, which the Chamber of Deputies had passed as early as 1895.
Current US bicameral flaws are also not new.