Read the passage by Peter N. Sterns.

The past causes the present, and so the future. Any time we try to know why something happened . . . we have to look for factors that took shape earlier.

According to the writer, why is it important to study history?

so we can see how things change over time
so we can understand how the present came to be
so we can learn interesting facts about the past
so we do not repeat mistakes of the past