I've been studying on an issue about which the Supreme Court of Virginia has cited more than once the "Commentaries on the Laws of England" by William Blackstone.
Blackstone's Commentaries were written in the 1760s. The four books were the leading sourcebook for aspiring lawyers until the end of the 19th Century. Blackstone was read by John Marshall and Thomas Jefferson. "Begin with Blackstone's Commentaries," Abraham Lincoln advised in 1860.
In Howell v. McAuliffe, the Supreme Court in an opinion by the Chief Justice explained that "William Blackstone 'constituted the preeminent authority on English law for the founding generation,'" and that the Founders relied heavily on his Commentaries.
By my count, the Supreme Court of Virginia has cited Blackstone's Commentaries in Howell and in sixteen other opinions since 2011, even though the Commentaries were written more than 250 years ago. I had a hearing the other day on an issue where the other side sought to distinguish a decision from the 1950s. "That's new law in Virginia," the Circuit Court judge observed, and I agreed.
Perhaps Lincoln's advice remains sound. The text of Blackstone's Commentaries (sometimes with star paging) is available in a number of places online, including something called the Online Library of Liberty, and in Google Books.