Why are we drawn toward certain persons, and they to us, as if we had always known each other? Is it a fact that we always have? Is there something, after all, in that much abused term “affinity”? . . . At all events, it is just as logical to look back upon fond associations, as it is to look forward to them. We believe that ties formed in this life will be continued in the life to come; then why not believe that we had similar ties before we came into this world, and that some of them, at least, have been resumed in this state of existence?
Orson F. Whitney, "The Undiscovered Country", Improvement Era, December 1919
We've all had moments, if we really contemplate over our lives, at least I've had such moments, that someone, or even something, we've never met in this life before, or never heard before, seems very familiar for some reason. Like what we are hearing or learning, and, who we are meeting, is recognizable and like we've heard that before or knew that person before... somewhere, at some time.

Why is that?
The Savior said that "my sheep hear my voice." (John 10:27)
Think about this for a second. Our spirits have a voice. Aside from the one that came with our mortal bodies. It may not be an audible voice but it was how we communicated before this life. And that voice is commanding and powerful, yet our now mortal voices often block it out. When Christ speaks to us, He speaks to our spirits, not our mortal ears. That's how we learned things in the pre-existence without a body. We "heard" Him and He knew us.
So, why then, would that be any different here? The only difference is that we are so caught up in mortal pursuits that we tend to drown out what our spirits hear. Christ is still speaking to us, teaching us. But we don't often hear Him. He still knows us, but do we know Him?
Man, and woman, is spirit (D&C 93:33). Right now, we also have a body, but we are spirit. We are intelligences. So, the question then becomes, are we actively suppressing our spirits and shutting that side up (for lack of a better phrase)? Or are we doing the opposite? And enlarging our spirits while suppressing our "natural man, and woman" frames?
That is the purpose of this life.