Old blog posts starts ranking again on its own: What is the likely reason?

[Trush Jodie]

At different times, I have seen an old blog post of like three years since it was first published start ranking again on search engines. No editing or anything on the blog post.

What could he the reason that an old blog post just starts to rank again?

 

[Min George]

Just maybe Google has done an algorithm change that re-evaluate that blog post and finds it to be useful. And it ranks higher.