The "valley" is a symbol of a blessed state of peace, spiritual balance, mental, psychological tranquility, gained by true knowledge and fulfillment of the Will of God, His Commandments. 

The word "Valley" also figuratively denotes the spiritual level of perception, human cognition of the "Heights" of the Wisdom of God's Will and the measure of its fulfillment.

 Negative meaning.

"The valley is a symbol of sorrow, sadness, the condition of people living according to their own, not God's Laws, being in a spiritually-dead, spiritually-normal, sinful state.

"The valley is the entire history of nations, filled with various sufferings, wars, social, political, religious conflicts, upheavals.