Can you explain this 'No man for any considerable period can wear one face to himself and another to the multitude without finally getting bewildered as to which may be the true'?

No one can live one life in public, and a different one in private without wondering which life is their true one. This quote means that one cannot life a double life without confusing the two after awhile. In the terms of the book The Scarlet LetterRoger Chillingworth tried to get close to Arthur Dimmesdale in order to torment him for having the affair with Hester, whilst under the guise of a physician taking care of the ailing minister. Eventualy, at the climax of the story, Roger makes a grand statement, about Arthur escaping his vengeance by revealing his dark secret on his, and reveals his true intents. He was unable to keep is dark plots separate from his caring facade and consequently served to make Dimmesdale seem even more impressive because he revealed is mistake willingly in an attempt at penance. Dimmesdale himself is also guilty of wearing a mask in public. His health begins to fail because he thinks himself a dastardly sinner, while at the same time believing that show the weakness of human nature to his community would be a betrayal to them. At the end his improper affair serves to make him appear even holier in the eyes of some of the townsfolk, for he showed them that no one is above sin; his two faces become mixed together into the person people think of him as after his death.