To begin with letter 3, It could be said that the main theme is determination because Walton feels confident about the voyage and he is ´determined' to go on with it despite the weather conditions.
As regards letter 4, we might say that the theme may be trust and friendship because Frankenstein and Walton met and he is will to tell him the his story. So this letter might be seen as the beginning of their friendship.
To let us know what the blue horse looks like and to add more description
Answer:
That is amazing!
Explanation:
Is that supposed to be a question???