What are the pros and cons of studying history? How can history be used to help understand what's going on? How can it be used to spread hate?

Some of the pros of studying history is that you know the past and can learn from the mistakes of others before you. You also understand your history a little better, making you appreciate it more. Your more advanced in subjects and it helps you understand present issues better because you know what caused them. A con of learning history is misunderstanding it.
History as an important part of our life, we live our lives around it feeding off of information we discovered in an earlier time than ours. It helps open doors by helping us understand the reason for something, like why it occurred. Helping us more forward instead of backwards. Sometimes people tend to use history and it's happenings to persuade people of hating a certain race or religion. By pining the blame on them. Thus creating more hate and spreading it by using events of the past and being biased towards the one race[s]. History has it's pros and cons, but it definitely has more pros.