Monuments vs. Courses and Distances
Justice Wilde, in Davis v. Rainsford, 17 Mass, 207 (1821) said:
Whenever known monuments are referred to as boundaries, they must govern, although neither courses, nor distances, nor the computed contents, correspond with the boundaries.
Accordingly, although without the benefit of survey we may never know the exact lengths of the sidelines of a particular parcel of property, their positions on the ground are certain and precise and define the land with utmost accuracy. (Here's a metaphor that I created and have used many times to explain this theory: When an Olympic athlete jumps and the coach marks with a stake the point where he or she has landed we can tell instantly the precise point where the athlete has vaulted, but until the coach measures the length with a yardstick we can not ascribe a mathematical representation to it. But, even after that distance is measured with the yardstick, whether accurately or not (and different coaches will come up with slightly different numbers), the athlete's point of impact will always be the same and can be precisely located at any time by reference to the position of the stake. The stake is the "monument," as to which we all agree marks the point of the athlete's impact, even though the numbers that the various coaches have written down are different.).