What Am I Riddles

Question: Cold and dark, I'm the same as my neighbor. Flatter than a pancake, faster than a panther. Lighter than a feather I still prevail, Yet a million mean trying to lift me would fail. Expanding and shrinking throughout the day, When heat is highest, underneath I lay. I leave in the darkness of the night, And don't come back if there's rain in sight. What am I?

Question: What lightens the light and darkens the dark?

Question: I support the fallen (ones) I restrain the naughty (ones) I replace the nonexistent (ones) What am I?

Question: I am the universe's complex elegance, I am everywhere...I am created through suffering, inspiration, joy, and even despair. I am born as an idea, and then presented to the human eye. However, unlike living things, I can never die. What am I?

Question: A man travels by wagon,
brings joy each evening,
but depression by the morning.

Who is he?