A simple subject completes the sentence, and the sentence can't be without it. In this case, the sentence would be "Bobby swam in the over the summer." It doesn't make sense right? So with that example, I'm pretty certain the answer is Lake :)
Contemporary is a more rational way of thinking that is the difference. Now a days no people don stick to the idea of fate they are more realistic now and come up with other ways for explaining things.
