When the religious rulers shown themselves to be dirty, Jesus' first act was to write in the dust with his finger. Perhaps in that moment the Lord was remembering something from before time when he created humans "from the dust of the ground".
John 8:3-11 tells of how the Pharisees brought a women caught in adultery before Jesus. She was placed in the center of a crowd of men eager to prove their superiority to Jesus. They kept asking him questions to trap him, but Jesus did not answer for he knew their hearts and he would not let them have power over him." (John 2:24)
Jesus knew the true nature of the people gathered there. They were willing to expose this woman in order to trap Jesus. They were without mercy. Their souls were corrupt, and their consciences knew it.
Jesus knew that they were but dust because, as John states, all things were made by/through (Greek: δια) Him. John 1:3 states that "All things were made through/by Him, and without Him was not anything made that was made."
From before time the Son of God was. He formed humans from the dust of the earth (Gen. 2:7) and the breath of God gave them life. Jesus spoke of His pre-existence (John 3:13; 6:33, 38, 62; 8:23; 16:28). Christ even said that He existed prior to Abraham.
Jesus was no ordinary man. His voice commanded the winds and the waves. With a simple word he healed the incurable. The one who came from Heaven, stooped to become one of us, but without sin.
In the story of the woman caught in adultery Jesus stoops to write with his finger in the dust. He said not a word. Then rising, he said to the accusers, "Let him who is without sin cast the first stone."
“No one, sir,” she said.
“Then neither do I condemn you,” Jesus declared. “Go now and sin no more.”
Related reading: Jesus is Messiah Indeed; BIBLICAL ANTHROPOLOGY: The Ancient Antecedents of Ash Wednesday