There are dark caves and without a lantern there is no way of knowing what is ahead.  People can try to make their way through without any light but all they know is the immediate surroundings.  They can only feel which causes them to miss any beauty or danger that is hidden.

It is the same with spiritual living.  Without the love of Jesus Christ people move ahead in life enjoying the things are immediate.  Some may save up for a nice house or work their way up the corporate ladder which serves a purpose only on earth.

As people grow to understand the love of Jesus Christ and His eternal future it starts to make more sense the little things done in love accumulate heavenly blessings.  This is the type of light that brightens the future and many can see this light in the lives of those who genuinely love others.

Matthew 6:22-23  New Living Translation

“Your eye is like a lamp that provides light for your body. When your eye is healthy, your whole body is filled with light.  But when your eye is unhealthy, your whole body is filled with darkness. And if the light you think you have is actually darkness, how deep that darkness is!