A seasonal visitor can know a place beautifully and know almost nothing about its winter.

Knowing a place in one season is knowing a version of it. The summer visitor can love it accurately and completely, and still have no idea what the same streets are in February, when the light goes early and the population thins and everything that made it charming is closed. Both experiences are real and only one of them is the whole thing.

This is worth applying to people too. If you have only ever seen someone during their good season, your knowledge is partial in the same way. Not wrong, just incomplete. Before making large decisions about a place or a person, it helps to have seen at least one winter.