Preface: I first encountered the bolded on p 220, Is Eating People Wrong? Great Legal Cases and How They Shaped the World (2011) by Allan C. Hutchinson.
Source: p 185, The Essential Holmes: Selections from [...] Oliver Wendell Holmes, Jr., edited by Richard Posner.
Original Source: Law in Science and Science in Law, 12 Harvard Law Review 443 (1899).
This process of historical explanation has been applied to the matter of our profession, especially Of recent years, with great success, and with so much eagerness, and with such a feeling that When you had true historic dogma you had the last word not only in the present but for the immediate future, that I have felt warranted heretofore in throwing out the caution that continuity with the past is only a necessity and not a duty. As soon as a legislature is able to imagine abolishing the requirement of a consideration for a simple contract, it is at perfect liberty to abolish it, if it thinks it wise to do so, without the slightest regard to continuity with the past. The continuity simply limits the possibilities of our imagination, and settles the terms in which we shall be compelled to think.
I do not comprehend the bolded: How is continuity even a necessity for the law, much less a duty? As Holmes himself states in the last sentence above, a legislature can ignore the past and create something entirely new; I also know that some activist judges can do so.