'Hashem- God appeared to Abraham in the plains of Mamre '. Since Hashem- God did not say anything the Sages learn that God ' came to visit the sick '. It was the 3rd and most painful day after Abraham's brit milah = circumcision. Abraham is sitting at the entrance of his tent in the heat of the day, so Hashem – God attending to the needs of the sick, makes sure that Abraham's desperate need for guests is addressed. Abraham saw the 3 angels in the guise of men coming, and then stopping as to indicate they did not want to trouble him. Abraham, despite the pain ran towards them to invite them in. The 3 angels were Michael - who informed Abraham that Sara would have a son, Gabriel would overturn Sodom and Raphael would heal Abraham and save Lot.
The obvious question is that if I would have a choice, I would prefer Hashem- God to be the doctor and do the healing and Raphael to do the mitzvah of visiting the sick. Further, from where did Abraham get the energy and strength to run towards the angels to invite them in?
The doctor is in fact the ' shaliach ' or God's agent who has been given the permission and help from God to heal. But the mitzvah of 'visiting the sick ' essentially cannot be done by an agent or a shaliach. If one cannot come, the sick person will always experience some disappointment. Just being there, has a positive impact on the emotions and therefore the health of the patient. One could always be more of a help and attend to his specific needs and requests and of course pray for the sick person asking that ' Heaven send a ' refuah Shelia – a total recovery – to the patient together with all the other sick people of Israel. The Talmudic Sages say that just being there has a healing effect, as the visitor removes one sixtieth of the illness in some mystical way. The research has an explanation for the healing effect of a visit – the placebo effect and impact on positive emotions. So it was the healing effect of God- Hashem visiting Abraham that gave him the strength to run towards the angels. There is the well- known placebo effect, where a positive attitude, expectations and belief that one has received an active treatment, even if the med is a placebo, impacts not only making the patient report feeling better as in the case of asthma, but in the cases of pain, depression, anxiety, fatigue, heart rate and blood pressure the 'placebo' can cause some objective physiological changes. The prayers, positive thoughts and emotional support that a visitor offers a patient, strengthens the patient's belief in his treatment and expectations to return to good health.
Emotions have a powerful effect on a patient's health, so close and supportive relationships and the accompanying positive emotions are reported to improve a patient's health - increase a person's resistance to illness and reduce the risk of having a another heart attack etc . When a visitor has a smiling face and is in a loving and cheerful mood, the patient becomes infected, as the patient's ' mirror neurons' mimic the emotions thereby lifting up the spirit of the patient and making him feel better. Love, kindness and caring can help a patient recover from ill health. When people and friends fail to turn up, they not only deprive patients of loving contact, but their feelings of rejection activate the very areas of the brain that generate the sting of physical pain.