A more thorough explanation:

Definition: Unity of seisin is when a person becomes the owner of a piece of land on which they already have an easement, resulting in the merging of ownership and easement rights into one person.

Example: John owns a large piece of land that includes a driveway used by his neighbor, Sarah, to access her property. Sarah has an easement allowing her to use the driveway. If John later purchases the portion of land that the driveway is on, he now has both ownership of the land and the easement rights. This is an example of unity of seisin.

Explanation: In this example, John already had an easement on his land that allowed Sarah to use the driveway. When John later purchased the portion of land that the driveway was on, he became the owner of the land and the easement rights. This means that John now has complete control over the land and the easement, and Sarah's right to use the driveway is now merged with John's ownership rights.