The Wind Blows Where It Wishes

In the early verses of John chapter 3, Jesus tells Nicodemus in no uncertain terms, the absolute necessity of being born again (or born from above). Yet, remarkably, He didn't then spell out what he must do to be born again. That is because it was not within Nicodemus' power to perform this miracle. Instead, the wind blows where it wishes. (What is all that about?)