Why is Your Spirit Cast Down?

“Why are you cast down, O my soul? And why are you disquieted within me? Hope in God, for I shall yet praise Him for the help of His countenance.”
Psalm 42:5 

It is said that the Devil once decided to go out of his business and he offered his tools for sale. They were attractively displayed: Trickery, Hatred, Jealousy, Malice, Deceit, Sensuality, and many other evil tools, each marked with a price. But in the center was a wedge-shaped, much worn tool priced higher than all the others. “What is that?” Satan was asked. “That is Discouragement,” he replied. “But why so costly?” “Because it can do my evil work better than all other tools. With it I can make the lives of many folks of no value. I can make then just lie down and ‘give up’ and become useless and they don’t even know I am the one who uses it”