He was there for Christopher Reeve during hard times.
Robin Williams and Christopher Reeve, who is best known for playing Superman, first met in college, and their friendship withstood the test of time. After Christopher Reeve had an accident that paralyzed him, Robin Williams supported his friend and cheered him up. It was actually Williams who made Reeve laugh for the first time since the accident, when he came to visit him at the hospital. He was also involved in The Christopher & Dana Reeve Foundation, which is dedicated to curing spinal cord injuries.
yea and look where that idea is today