Where does fear come from?
It comes from uncertainty. For example, you will be afraid if you are uncertain if there is light at the end of the tunnel. However, if you know in advance that there is light at the end of the tunnel, you will have reassurance while going through the tunnel.
Another example could be a child may be born talented in music, however without knowing this, the parent might force the child to go into medical and spend tremendous time, money and energy that might not yield any results. On the other hand, if you know in advance regarding the child’s strength, the parent can focus and go full steam ahead in that direction without wasting resources.
These are the difference in knowing in advance. You can mentally, emotionally, and physically prepare yourself in certain situations.