Why did Helen feel an instant rapport with Dr. Alexander Graham bell? How was Dr. Bell instrumental in opening for Helen the door leading from darkness to light?

Helen felt the tenderness and sympathy in Dr. Bell's behaviour, which touched her tender heart.  He held Helen on his knee while she examined his watch, and he made it strike for her. He understood Helen's signs, which made her love him at once. That interview opened the door through which Helen should pass from darkness into light, from isolation to friendship, companionship, knowledge, love. Dr. Bell advised Helen's father to write to Mr. Anagnos, director of the Perkins Institution in Boston, the scene of Dr. Howe's great labours for the blind, and ask him if he had a teacher competent to teach Helen, and in a few weeks there came a kind letter from Mr. Anagnos with the comforting assurance that a teacher had been found. With the arrival of Miss Sullivan, Helen experienced light with which she had been deprived after her sickness.