If someone harks back to something in the past, they talk about it again and again, often in a way that annoys other people.

He's always harking back to his childhood and saying how things were better then. 他老是提起他的童年，说那时一切都比现在好。

If something harks back to something in the past, it is similar to it.

The director's latest film harks back to the early years of cinema. 那个导演的新片与早期电影的风格类似。