 This stream of work on DST must be counted among the most important contributions made by set theory to analysis and topology. But what had begun as an attempt to prove the Continuum Hypothesis could not reach this goal. Soon it was shown using the Axiom of Choice that there are non-Lebesgue measurable sets of reals (Vitali 1905), and also uncountable sets of reals with no perfect subset (Bernstein 1908). Such results made clear the impossibility of reaching the goal of CH by concentrating on definable and “well-behaved” sets of reals.