For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
I think one should take into consideration where Jesus was at the time and when he actually started writing on the ground. First it says he was in the temple so the floor in the temple would have been stone. Next he started writing only after they asked him the question in relation to the law.
I can only speculate that he was trying to show that He gave the law and they were trying to trick the giver of the law. However this is only speculation.
In the end the focus is not on what was being written on the ground but a host of other lessons.
Jesus was teaching when the leaders came to him with the lady. They accused her of adultery and said that the law required that she be stoned to death. Jesus then knelt and began writing in the dirt. What he wrote is not written in any of the gospels. What was written was not important. It may have been that he was writing a list of the sins of the men standing there. The Bible says that the men, from the oldest to the youngest, left. When the last one left, Jesus asked where her accusers were. She said they were gone and Jesus told he that he did not accuse her either and told her to go and sin no more.
The lesson here for all of us is that we see others' sins much easier that we see our own. When we take our time we can see our sins also and know that we are no better that anyone else. Our calling is to love each other and encourage each other just as Jesus did when he did not condemn the lady but loved her and encouraged her by telling her to go and sin no more.
#Adultery - just letting those around Him know He knew who they really were. OK, so they didn't have Twitter yet, but I'm sure that it was something they all could see and understand that He knew their guilt.
The woman caught in adultery, and being brought to Jesus was a clear indication that they were trying to trap and accuse Him of the law written down by Moses.
Jesus often would stand up to read the scrolls given to him in the synagogue and would teach them (Luke 4:15). The Jewish elders and the scribes were well versed in the books of the law and the prophets and he would often quote “as it is written” for them to know that it was not some new doctrine that he was preaching but something which they all had read and heard in the synagogue.
Being well versed in the scriptures, yet they bring only the woman and not the man, which indicates their motives. For the scripture says in Isaiah 55:6-7 "Seek the Lord and he will pardon your sins." All they cared about was to please God with their outwardly works and sacrifices, and they had no mercy (Mat 9:13).
For the Father's will Jesus was sent (John 6:38) and as it is written of Him "Lo, I come in the volume of the book it is written of me, to do thy will. O God." (Heb 10:7) And Jesus said, "For judgment I am come into this world, that they which see not might see; and that they which see might be made blind." (John 9:39-41).
The Pharisees brought the woman to be stoned to death, and they didn't hear and repent, for Jesus was speaking to them very clearly that those who have not sinned should be the first to throw a stone, but they walked away without repenting. For as it is written in the book of Jeremiah 17:13 "O Lord, the Hope of Israel, all that forsake thee shall be ashamed, and they that 'depart from me shall be WRITTEN in the earth', because they have forsaken the Lord, the fountain of living waters."