Who is Susan from The Waves and what is their importance?

Susan is described as strong and motherly. She prefers the country to the city, and she quickly marries and has a family. Susan talks about walking outside in the fresh air, and the way the seasons all seem to roll into one. Bernard tells us that Susan once admitted to being a failure, and that she hadn't achieved everything she could of done. It is obvious, however, that more than anyone she made the right choice for herself.