Something more concrete than theories about Moses dropping acid would be an atempt to diagnose Saul/Paul and his conversion experience.
Acts 9
1Meanwhile, Saul was still breathing out murderous threats against the Lord's disciples. He went to the high priest 2and asked him for letters to the synagogues in Damascus, so that if he found any there who belonged to the Way, whether men or women, he might take them as prisoners to Jerusalem. 3As he neared Damascus on his journey, suddenly a light from heaven flashed around him. 4He fell to the ground and heard a voice say to him, "Saul, Saul, why do you persecute me?"
5"Who are you, Lord?" Saul asked.
"I am Jesus, whom you are persecuting," he replied. 6"Now get up and go into the city, and you will be told what you must do."
7The men traveling with Saul stood there speechless; they heard the sound but did not see anyone. 8Saul got up from the ground, but when he opened his eyes he could see nothing. So they led him by the hand into Damascus. 9For three days he was blind, and did not eat or drink anything.
10In Damascus there was a disciple named Ananias. The Lord called to him in a vision, "Ananias!"
"Yes, Lord," he answered.
11The Lord told him, "Go to the house of Judas on Straight Street and ask for a man from Tarsus named Saul, for he is praying. 12In a vision he has seen a man named Ananias come and place his hands on him to restore his sight."
13"Lord," Ananias answered, "I have heard many reports about this man and all the harm he has done to your saints in Jerusalem. 14And he has come here with authority from the chief priests to arrest all who call on your name."
15But the Lord said to Ananias, "Go! This man is my chosen instrument to carry my name before the Gentiles and their kings and before the people of Israel. 16I will show him how much he must suffer for my name."
17Then Ananias went to the house and entered it. Placing his hands on Saul, he said, "Brother Saul, the Lord—Jesus, who appeared to you on the road as you were coming here—has sent me so that you may see again and be filled with the Holy Spirit." 18Immediately, something like scales fell from Saul's eyes, and he could see again. He got up and was baptized, 19and after taking some food, he regained his strength.
If Saul was a young, zealous Jew going WAY out of his way to persecute Jews who followed Jesus, I'd say something was emotionally akilter with this man. He was not satisfied with studying and teaching or living a normal, Jewish life. He either wanted to gain reputation as a leader or was sincerely upset with early Christians. He took his religious beliefs so far as to police others when there were at that time a wide variety of Jewish beliefs and practices.
If Saul was a very moral individual, he may have come to a point in his life when his view of the world expanded or when his level of empathy for others different from himself had increased. His actions may have come to weigh on him very heavily. People who are VERY committed to a worldview or feel very ashamed of their actions will often become even more extreme in an attempt to compensate for their doubts and insecurities. An example of this might be a homosexual man ashamed of his inclinations who tries harder and harder to appear heterosexual and even harshly condemns other homosexuals. This could have led Saul to a point of emotional and mental exhaustion.
People who are confronted with things they are emotionally unwilling to accept can sometimes experience physical symptoms from the stress. One situation is called conversion disorder. In this situation, blindness, deafness, and motor problems can be experienced for an indefinite time. One of the treatments is an attempt to calm the patient or help relieve them of the psychological factors that led to their depression.
If Saul felt incredibly guilty for his role in causing harm to nice followers of Jesus, and he responded to that by becoming even more zealous, he may have caused his own emotional 'breakdown' and subsequent blindness. Ananias may have helped him out of his depression by the offer of forgiveness. And then a zealous preacher for Jesus is born. Saul goes native and becomes Paul.
http://en.wikipedia.org/wiki/Conversion_disorder