At the adoption of the Constitution, this rule, promulgated in the Court of King’s Bench by the voice of the most finished magistrate in English history, was as well known in our country as any principle of the Common Law; especially was it known to the eminent lawyers in the Convention; nor is it too much to say that the Constitution was framed with this rule on Slavery as a guide. And the Supreme Court of the United States, at a later day, by the lips of Chief-Justice Marshall, promulgated this same rule, in words stronger even than those of Lord Mansfield, saying: “Where rights are infringed, where fundamental principles are overthrown, where the general system of the laws is departed from, the legislative intention must be expressed with _irresistible clearness_, to induce a court of justice to suppose a design to effect such objects.”[127] It is well known, however, that these two declarations are little more than new forms for the ancient rule of the Common Law, as expressed by Fortescue: _Impius et crudelis judicandus est qui Libertati non favet_: “He is to be adjudged impious and cruel who does not favor Liberty,”[128]--and as expressed by Blackstone, “The law is always ready to catch at anything in favor of Liberty.”[129] But, as no prescription runs against the King, so no prescription is allowed to run against Slavery, while all the early victories of Freedom are set aside by the Slave-Masters of to-day. The prohibition of Slavery in the Missouri Territory, and all the precedents, legislative and judicial, for the exercise of this power, admitted from the beginning until now, are overturned. At last, bolder grown, Slave-Masters do not hesitate to assail that principle of jurisprudence which makes Slavery the creature of “positive law” alone, to be upheld only by words of “irresistible clearness.” The case of Somerset, in which this great rule was declared, is impeached on this floor, as the Declaration of Independence is also impeached. And here the Senator from Louisiana [Mr. BENJAMIN] takes the lead, with the assertion, that in the history of English law there are earlier cases, where a contrary principle was declared. Permit me to say that no such cases, even if hunted up in authentic reports, can impair the influence of this well-considered authority. The Senator knows well that an old and barbarous case is a poor answer to a principle brought into activity by the demands of advancing Civilization, and which, once recognized, can never be denied. Pardon me, if I remind him that Jurisprudence is not a dark-lantern, shining in a narrow circle, and never changing, but a gladsome light, which, slowly emerging from original darkness, grows and spreads with human improvement, until at last it becomes as broad and general as the Light of Day. When the Senator, in this age, leaguing all his forces, undertakes to drag down that immortal principle which made Slavery impossible in England, as, thank God! it