Why does pain exist?
Perhaps to beckon gratitude when nothing is hurting.
Maybe to identify something that may not be working properly, or what is not right.
Pain brings appreciation for times of health and healing.
Pain is an indicator.
Why does darkness exist?
Physically speaking, the earth's vegetation needs rest from the sun's rays, otherwise life wouldn't function properly.
How can one appreciate the light if the darkness cannot be adequately identified as dark?
Things get lost in the dark.
When the light is on, those lost things can be found.
Without something being previously lost, the anguish and discomfort from the loss cannot be identified, and thus the finding of what is lost cannot be appreciated.
The desire to not lose, or allow some thing to be lost, cannot be desired.
The darkness accentuates the light.
Why does death happen and exist?
If a leaf does not 'die' and fall to the ground, how would the insects, the soil and the very tree the leaf fell from be nourished?
Without a seed falling to the ground, new life would not occur.
Death seems to be an occurrence which precedes life and completes the cycle of life.
Death sprouts the desire to live, and live this life to the fullest.
Death magnifies life.
Why does hate exist?
Fear and ignorance.
The human can be quick to hate what causes fear, like another human, an animal, or what another human has told them, teaching them to fear something unknown.
Jealousy and envy.
There is always someone smarter, someone more talented and someone more highly gifted.
Instead of appreciating, learning from and developing in what is lacking, to hate is to fail at the triggering emotions jealousy rouses.
Wise choices after emotions are triggered is crucial to conquering the human condition.