Unknown

I remember what Joel taught me, willingness to accept "unknown."  That is really profound.

"Unknown" makes those who don't live in a present moment feel fear, because their focus is always on either the future or the past.  They are always interested in or concerned about the future, and try to prepare for anything possible for the future to make themselves feel content or to be released from worry.

"Unknown" may make those who got spiritual awaken feel exhilarated, because it means infinite possibility to them.  They focus on the present moment without bothering about the future. 
Actually, now and here, the future even doesn't exist, but only the present moment exists.  The future exist only in our mind, which is very illusion.

That's right!  Like Robert Scheinfeld says, we all make ourselves being limited and conditioned as much as possible in Phase 1.  That's why "unknown" causes fear.  If we are liberated from such limitation and conditioning, we all are free, and then "unknown" means exhilarating jack-in-a-box!