As Clarke notes in his Commentary:
The parched ground "The glowing sand"...sharab; this word is Arabic, as well as Hebrew, expressing in both languages the same thing, the glowing sandy plain, which in the hot countries at a distance has the appearance of water.
"And the mirage hath become a pond" (Isa 35.7a YLT)What a cruel deception for a dying traveler to race toward desert pool, only to find that his dream of water dashed by the realization that the pool is a mirage!
I can think of something even more cruel: for a spiritual sojourner, crazed with burning thirst, to race toward spiritual water, only to find nothingness for his soul.
All of the religions of the world offer nothing more but mirages of soul satisfaction; none deliver on the promises but Christianity.
Thomas said to him, "Lord, we do not know where you are going. How can we know the way?" Jesus said to him, "I am the way, and the truth, and the life. No one comes to the Father except through me." (John 14.5-6 ESV)Thirsty soul, run toward Jesus Christ; he is no mirage but, rather, a cool drink of water.