"First, he argued that “there is no proof of life [with a fetus] in the sense that the law contemplates proof of fact.” That would have surprised the English and American courts that applied two common-law evidentiary rules: the quickening rule (as first evidence of life) and the born-alive rule (for proof that a criminal act had caused the death). It also would have surprised the prosecutor in the Keeler case, who proved beyond a reasonable doubt that the perpetrator killed the child while unborn. Second, Clark asked: “Does it therefore follow that voluntary destruction of the fetus is also [prevented[ from interference by the State? Perhaps-unless life is present. . . . “ The entire motivation of the movement to eliminate the quickening rule across the states in the mid-nineteenth century-led by the medical profession-was the biological evidence tat the life of each child began at conception, not quickening, and the state statutes were explicitly amended to adopt conception. Third, Clark’s most famous sentence-quoted by Justice Brennnan to Douglas in December 1971 and by Justice Blackmun in Roe-begged the evidentiary question that the nineteenth-century state legislatures expressly decided: “To say that life is present at conception is to give recognition to the potential, rather than the actual. . . . But the law deals in reality, not obscurity-the known rather than the unknown.” What Clark considered an abstraction in 1969 had been adopted as the law by the people of numerous states a century before and reiterated in numerous court decisions and statutes by 1969."