Do not capitalize the first item after the colon (unless it's a proper noun).
Rule 1a, Use a colon to introduce an item or a series of items.
Colons and semicolons should never be used interchangeably.
I think that Hellen Keller was a very loud and outspoken person for someone her age and with her conditions. My thought about this is that it is what she uses to try and comunicate with other people to make sure that they would still notice her.